Fix f16 matmul interface

- Move lhs_stride position in the list of input arguments
- Add dst_stride_col in the list of input arguments
- Add the interface header file

Signed-off-by: Gian Marco Iodice <gianmarco.iodice@arm.com>

Approved-by: Viet-Hoa Do <viet-hoa.do@arm.com>