arm64: enable test cases for:
{uqshl, sqshl, sqshlu} (vector, imm)
{uqshl, sqshl, sqshlu} (scalar, imm)
{uqshrn, sqrshrun, sqshrun} (scalar, imm)



git-svn-id: svn://svn.valgrind.org/valgrind/trunk@14281 a5019735-40e9-0310-863c-91ae7b9d1cf9