libmctp-intel: fix tests

Summary:
The current revision of code upstream in this repository
appears to fail to compile with later versions of GCC.  Fix them.

```
| build-halfdome/tmp/work/armv7at2hf-vfp-fb-linux-gnueabi/libmctp-intel/1.0+gitAUTOINC+d530c2271e-r1/git/tests/test_astlpc.c:98:26: error: array subscript 2 is above array bounds of 'uint8_t[2]' {aka 'unsigned char[2]'} [-Werror=array-bounds]
|    98 |                 mmio->kcs[reg] = val;
|       |                 ~~~~~~~~~^~~~~
| build-halfdome/tmp/work/armv7at2hf-vfp-fb-linux-gnueabi/libmctp-intel/1.0+gitAUTOINC+d530c2271e-r1/git/tests/test_astlpc.c:63:17: note: while referencing 'kcs'
|    63 |         uint8_t kcs[2];
```

Submitted upstream at Intel-BMC/libmctp#1

Test Plan: Build passes.

Reviewed By: GoldenBug

fbshipit-source-id: d48d3c787bccea767d29de8879c72ac93e20961f

Author: williamspatrick

common/recipes-lib/mctp/files/0004-test-astlpc-fix-compile-warning.patch

@@ -0,0 +1,37 @@
+From 197fb58e40863ad07cc571c7a38e6581f74ee09f Mon Sep 17 00:00:00 2001
+From: Patrick Williams <patrick@stwcx.xyz>
+Date: Mon, 13 Jun 2022 17:12:03 -0500
+Subject: [PATCH] test: astlpc: fix compile warning
+
+With the GCC found in openbmc/openbmc master, we are observing the
+following:
+
+```
+    | build-halfdome/tmp/work/armv7at2hf-vfp-fb-linux-gnueabi/libmctp-intel/1.0+gitAUTOINC+d530c2271e-r1/git/tests/test_astlpc.c:98:26: error: array subscript 2 is above array bounds of 'uint8_t[2]' {aka 'unsigned char[2]'} [-Werror=array-bounds]
+    |    98 |                 mmio->kcs[reg] = val;
+    |       |                 ~~~~~~~~~^~~~~
+    | build-halfdome/tmp/work/armv7at2hf-vfp-fb-linux-gnueabi/libmctp-intel/1.0+gitAUTOINC+d530c2271e-r1/git/tests/test_astlpc.c:63:17: note: while referencing 'kcs'
+    |    63 |         uint8_t kcs[2];
+```
+
+Fix this by being explicit about the register access (enum to int map).
+---
+ tests/test_astlpc.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/tests/test_astlpc.c b/tests/test_astlpc.c
+index 0e0dcca..9ecd787 100644
+--- a/tests/test_astlpc.c
++++ b/tests/test_astlpc.c
+@@ -94,7 +94,7 @@ int mctp_astlpc_mmio_kcs_write(void *data, enum mctp_binding_astlpc_kcs_reg reg,
+ 
+ 	if (reg == MCTP_ASTLPC_KCS_REG_STATUS)
+ 		mmio->kcs[reg] = val & ~0xaU;
+-	else
++	else if (reg == MCTP_ASTLPC_KCS_REG_DATA)
+ 		mmio->kcs[reg] = val;
+ 
+ 	mctp_prdebug("%s: 0x%hhx to %s", __func__, val,
+-- 
+2.31.1
+

common/recipes-lib/mctp/libmctp-intel_git.bb

@@ -11,6 +11,7 @@ SRC_URI = "git://github.com/Intel-BMC/libmctp.git;protocol=https;branch=master \
            file://0001-Remove-unknown-i2c-smbus.h.patch \
            file://0002-Build-as-shared-library.patch \
            file://0003-Customize-buffer-size.patch \
+           file://0004-test-astlpc-fix-compile-warning.patch \
           "
 SRCREV = "d530c2271e1f9ff5d76a170c0abd64bd03ef40fd"
 SRC_URI[md5sum] = "1c7db87fb8fa946b03d91fff08b0825a"