RISC-V: Fix warning in predicated.md

RISC-V: Fix warning in predicated.md

Notice there is warning in predicates.md:
../../../riscv-gcc/gcc/config/riscv/predicates.md: In function ‘bool arith_operand_or_mode_mask(rtx, machine_mode)’:
../../../riscv-gcc/gcc/config/riscv/predicates.md:33:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             (match_test "INTVAL (op) == GET_MODE_MASK (HImode)
../../../riscv-gcc/gcc/config/riscv/predicates.md:34:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     || INTVAL (op) == GET_MODE_MASK (SImode)"))))

gcc/ChangeLog:

	* config/riscv/predicates.md: Change INTVAL into UINTVAL.