testsuite/116654 - adjust gcc.target/powerpc/p9-vec-length-full-8.c

testsuite/116654 - adjust gcc.target/powerpc/p9-vec-length-full-8.c

gcc.target/powerpc/p9-vec-length-full-8.c was expecting all loops to
use -with-len fully masked vectorization to avoid epilogues because
the loops needed peeling for gaps.  With SLP we have improved things
here and the loops using V2D[IF]mode no longer need peeling for gaps
since the target can compose those vectors from two scalars and
in turn we generate better code and not need an epilogue either
(the iteration count divides by the VF).

	PR testsuite/116654
	* gcc.target/powerpc/p9-vec-length-full-8.c: Adjust.