drivers/pcie: Add a function for dynamic PCIe IRQ connection

The is meant to fix a chicken & egg issue with MSI interrupt remapping.
Currently, drivers first connect the irq (by-passing any possible MSI
remapping), so the IRQ ends-up being remapped at the IOAPIC level which
is not what we want.

So adding a dedicated function to properly handle this case. This is
valid only for runtime dynamic IRQ connection obviously.

Signed-off-by: Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>