Update operand constraint and tests for cv.shuffle.sci.h

gas/

	* testsuite/gas/riscv/cv-simd-march-fail.l: Update for
	cv.shuffle.sci.h which should error if more than 2 bits specified
	for the immediate to match architecture specification.
	* testsuite/gas/riscv/cv-simd-march-fail.s: Likewise.
	* testsuite/gas/riscv/cv-simd-march-xcvsimd.d: Likewise.
	* testsuite/gas/riscv/cv-simd-march-xcvsimd.s: Likewise.
	* testsuite/gas/riscv/cv-simd-shuffle-sci-h-fail.l: Likewise.
	* testsuite/gas/riscv/cv-simd-shuffle-sci-h-pass.d: Likewise.
	* testsuite/gas/riscv/cv-simd-shuffle-sci-h-pass.s: Likewise.

opcodes/

	* riscv-opc.c: Fix operand constraint for cv.shuffle.sci.h

Signed-off-by: Jeremy Bennett <jeremy.bennett@embecosm.com>