Check avx upper register for parallel.

Check avx upper register for parallel.

For function arguments/return, when it's BLK mode, it's put in a
parallel with an expr_list, and the expr_list contains the real mode
and registers.
Current ix86_check_avx_upper_register only checked for SSE_REG_P, and
failed to handle that. The patch extend the handle to each subrtx.

gcc/ChangeLog:

	PR target/116512
	* config/i386/i386.cc (ix86_check_avx_upper_register): Iterate
	subrtx to scan for avx upper register.
	(ix86_check_avx_upper_stores): Inline old
	ix86_check_avx_upper_register.
	(ix86_avx_u128_mode_needed): Ditto, and replace
	FOR_EACH_SUBRTX with call to new
	ix86_check_avx_upper_register.

gcc/testsuite/ChangeLog:

	* gcc.target/i386/pr116512.c: New test.

(cherry picked from commit ab214ef734bfc3dcffcf79ff9e1dd651c2b40566)