Optimize QAI8DXP LHS quant and pack micro-kernel using Arm® Neon™

Signed-off-by: Anitha Raj <anitha.raj@arm.com>

Reviewed-by: Anitha Raj <anitha.raj@arm.com>
Reviewed-by: Emil Ohlsson <emil.ohlsson@arm.com>
Reviewed-by: alankelly <alankelly@google.com>
Approved-by: Jakub Sujak <jakub.sujak@arm.com>