testsuite: Remove xfail gcc.dg/tree-ssa/pr91091-2.c RHS ! natural_alignment_32

Reacting to a long-standing XPASS for CRIS.  This one is
slightly brown paper-bag level; it was never the here-removed
xfailed scan that failed and I didn't notice that XPASS when
reporting success on the commit as a whole.  It's not logical to
re-read what was just-written even with overlap issues, and I'm
sure that edit was originally a copy-pasto.  I checked
historical m68k-linux and pru-elf test-results too, to verify
that I got that part right.

	PR testsuite/91419
	* gcc.dg/tree-ssa/pr91091-2.c:15 Remove xfail for RHS.