RISC-V: Reconcile the existing test for vdiv.vx combine

RISC-V: Reconcile the existing test for vdiv.vx combine

Some existing vdiv related test need some adjust for the
asm check.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/autovec/binop/vdiv-rv32gcv-nofm.c: Adjust
	the asm check for vdiv.
	* gcc.target/riscv/rvv/autovec/binop/vdiv-rv32gcv.c: Ditto.
	* gcc.target/riscv/rvv/autovec/binop/vdiv-rv64gcv-nofm.c: Ditto.
	* gcc.target/riscv/rvv/autovec/binop/vdiv-rv64gcv.c: Ditto.

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