Add irq related functions to register,handle,release,disable interrupt.

qca4019 supports msi interrupt, but it has the problem. Until the issue
gets sorted out, only legacy interrupt model is enabled and used.
Signed-off-by: Raja Mani <rmani@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>