Fix fold-vec-splat-floatdouble testsuite failure on power10

Fix fold-vec-splat-floatdouble testsuite failure on power10

When I added support for generating XXSPLTIDP on December 15th, 2021, I
missed updating the fold-vec-splat-floatdouble.c test to add to the regex
for the instructions generated.  This patch fixes that.

2022-01-20  Michael Meissner  <meissner@the-meissners.org>

gcc/testsuite/

	PR testsuite/103763
	* gcc.target/powerpc/fold-vec-splat-floatdouble.c: Fix insn regex
	on power10.