[ThpsPsx] Fix uneven padded texture data

[DCxDemo]

Whenever the width is not even, it's padded. probably to 2 pixels in 8 bit mode and 4 pixels in 4 bit mode.
Since it simply copies the data from bitmap, it gets a bit shifty.

A rare case, since textures should use power of 2 to be laid out properly in vram, but still annoying.