Update the QAI8 matmul interface

The QAI8 interface doesn't match the interface of the actual kernel.
This change changes the interface to align with the kernel, and then
enforces the interface alignment using unit testing.

Signed-off-by: Emil Ohlsson <emil.ohlsson@arm.com>

Approved-by: Jakub Sujak <jakub.sujak@arm.com>
Approved-by: Anton Bondarenko <anton.bondarenko@arm.com>