MIPS: Enable MSA

It is really dangerous to fallback to Loongson core on other
MIPS64 processors.

Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>

1. Using core loongson3r3 and loongson3r4 for loongson
2. Add DYNAMIC_ARCH for loongson

Change-Id: I1c6b54dbeca3a0cc31d1222af36a7e9bd6ab54c1

Using "make TARGET=GENERIC" on loongson platform will get the following
error messages:
"make[1]: *** No rule to make target 'sgemm_incopy.o', needed by 'libs'"
Add kernel/mips64/KERNEL.generic to slove the problem.

the fallbacks from Makefile.L1 assume a combined source for absolute value and non-absolute (with ifdef USE_ABS) but here we have separate implementations

as trivial copy of ?asum with the fabs replaced by mov to preserve code structure

neglected to rebase #1892 on merging

revert MIPS64 xDOT kernel changes from #1832

as the failures seen on Loongson3A appear to be limited to DSDOT/SDSDOT (i.e. my hackish "fix" from #1684)

as discussed in #1834

64bit push/pop register command should be used. Otherwise, data will lost.

Signed-off-by: Shivraj Patil <shivraj.patil@imgtec.com>

Signed-off-by: Shivraj Patil <shivraj.patil@imgtec.com>

Seperated mips and mips64 files.
Configurations support for mips 32 bit.

Signed-off-by: Shivraj Patil <shivraj.patil@imgtec.com>

Signed-off-by: Timothy Gu <timothygu99@gmail.com>