csky: Fixup vdsp&fpu issues in kernel

This fixup is continue to commit 35ff802a (csky: fixup remove
vdsp implement for kernel.) and in that patch I didn't finish the
job. We must forbid gcc to generate any vdsp & fpu instructions
and remove vdsp asm in memmove.S.

eg: For GCC it's -mcpu=ck860 and For AS it's -Wa,-mcpu=ck860fv

Signed-off-by: Guo Ren <ren_guo@c-sky.com>