aarch64: Implement simd SHL immediate support

C6.3.222 SHL scalar variant instruction

Signed-off-by: Lan Yixun (dlan) <dennis.yxun@gmail.com>
aarch64: Enable NEG insn support which is already implemented

C6.3.184 NEG scalar variant instruction

Signed-off-by: Lan Yixun (dlan) <dennis.yxun@gmail.com>
aarch64: Enable USHL insn support which is already implemented

C6.3.338 USHL scalar variant instruction

Signed-off-by: Lan Yixun (dlan) <dennis.yxun@gmail.com>
aarch64: Implement CMEQ(zero) scalar insn

C6.3.20 CMEQ(zero) scalar

Signed-off-by: Lan Yixun (dlan) <dennis.yxun@gmail.com>