bus/fsl-mc: Export IRQ pool handling functions to be used by VFIO

The IRQ pool handling functions can be used by both DPRC
driver and VFIO. Adapt and export those functions.

Reviewed-by: Laurentiu Tudor <laurentiu.tudor@nxp.com>
Acked-by: Laurentiu Tudor <laurentiu.tudor@nxp.com>
Signed-off-by: Diana Craciun <diana.craciun@oss.nxp.com>
Link: https://lore.kernel.org/r/20200929085441.17448-12-diana.craciun@oss.nxp.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>