rs6000: Disable MMA if no VSX support [PR103627]

rs6000: Disable MMA if no VSX support [PR103627]

As PR103627 shows, there is an unexpected case where !TARGET_VSX
and TARGET_MMA co-exist.  As ISA3.1 claims, SIMD is a requirement
for MMA.  By looking into the ICE, I noticed that the current
MMA implementation depends on vector pairs load/store which use
VSX register, but we don't have a separated option to control
Power10 vector support and Segher pointed out "-mpower9-vector is
a workaround that should go away" and more explanations in [1].
So this patch makes MMA require VSX instead.

[1] https://gcc.gnu.org/pipermail/gcc-patches/2022-January/589303.html

gcc/ChangeLog:

	PR target/103627
	* config/rs6000/rs6000.cc (rs6000_option_override_internal): Disable
	MMA if !TARGET_VSX.

gcc/testsuite/ChangeLog:

	PR target/103627
	* gcc.target/powerpc/pr103627-1.c: New test.
	* gcc.target/powerpc/pr103627-2.c: New test.