RISC-V: Adjust test case due to allow vwcvt[u].x.x.v overlap

Remove the xfail due to vwcvt changes.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/base/pr112431-1.c: Remove xfail.
	* gcc.target/riscv/rvv/base/pr112431-2.c: Ditto.
	* gcc.target/riscv/rvv/base/pr112431-3.c: Ditto.
	* gcc.target/riscv/rvv/base/pr112431-39.c: Ditto.
	* gcc.target/riscv/rvv/base/pr112431-40.c: Ditto.
	* gcc.target/riscv/rvv/base/pr112431-41.c: Ditto.

Signed-off-by: Pan Li <pan2.li@intel.com>