Add intrinsics for FEAT_SME_MOP4

[Lukacma]

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[jthackray]

LGTM

[CarolineConcatto]

Remember to change to alpha

[CarolineConcatto]

nit: remove that

[CarolineConcatto]

Maybe we can replace to something like this:
These intrinsics have an additional ‘_{1,2}x{1,2}’ suffix in non-overloaded names to indicate the order between single and multi-vector arguments.

[Lukacma]

I find that wording confusing. This suffix is not related to order of operands. Rather it tells which of the 2 vector operands are single and which are multi vectors. Maybe it could be like this:

These intrinsics use a _{1,2}x{1,2} suffix in non-overloaded names. The first number indicates whether the first vector argument is a single vector (1) or a pair of vectors (2). The second number follows the same rule for the second vector argument.

[CarolineConcatto]

s/[_f8]/[_mf8]/
It is missing the _fpm intrinsic at the end.
And should these intrinsics be also consistent with the non-FP8.