Remove -mno-spe flags as they dont belong

For some unknown reason at Steven Rostedt added in disabling of the SPE
instruction generation for e500 based PPC cores in commit
6ec562328fda585be2d7f472cfac99d3b44d362a.

We are removing it because:

1. It generates e500 kernels that don't work
2. its not the correct set of flags to do this
3. we handle this in the arch/powerpc/Makefile already
4. its unknown in talking to Steven why he did this

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Tested-and-Acked-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>