RISC-V: Simplify ASM checks in gcc.target/riscv/rvv/base/.

RISC-V: Simplify ASM checks in gcc.target/riscv/rvv/base/.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/base/mov-1.c: Simplify operand check.
	* gcc.target/riscv/rvv/base/mov-10.c: Ditto.
	* gcc.target/riscv/rvv/base/mov-11.c: Ditto.
	* gcc.target/riscv/rvv/base/mov-12.c: Ditto.
	* gcc.target/riscv/rvv/base/mov-2.c: Ditto.
	* gcc.target/riscv/rvv/base/mov-3.c: Ditto.
	* gcc.target/riscv/rvv/base/mov-4.c: Ditto.
	* gcc.target/riscv/rvv/base/mov-5.c: Ditto.
	* gcc.target/riscv/rvv/base/mov-6.c: Ditto.
	* gcc.target/riscv/rvv/base/mov-8.c: Ditto.
	* gcc.target/riscv/rvv/base/mov-9.c: Ditto.
	* gcc.target/riscv/rvv/base/vread_csr.c: Ditto.
	* gcc.target/riscv/rvv/base/vsetvl-1.c: Ditto.
	* gcc.target/riscv/rvv/base/vwrite_csr.c: Ditto.