RISC-V/testsuite/pr111466.c: update test and expected output

RISC-V/testsuite/pr111466.c: update test and expected output

Update the test to potentially generate two SEXT.W instructions: one for
incoming function arg, other for function return.

But after commit 8eb9cdd14218
("expr: don't clear SUBREG_PROMOTED_VAR_P flag for a promoted subreg")
the test is not supposed to generate either of them so fix the expected
assembler output which was errorneously introduced by commit above.

gcc/testsuite/ChangeLog:
	* gcc.target/riscv/pr111466.c (foo2): Change return to unsigned
	int as that will potentially generate two SEXT.W instructions.
	dg-final: Change to scan-assembler-not SEXT.W.

Signed-off-by: Vineet Gupta <vineetg@rivosinc.com>