LinuxKPI: pci: implement pcim_iomap()

Like pci_iomap() add the devres version pcim_iomap() using the former
to get the resource.

Add a helper function to validate that the bar is within a valid range
and sprinkle that check also to other related functions.

Sponsored by: The FreeBSD Foundation (intially)
MFC after: 3 days
Reviewed by: dumbbell
Differential Revision: https://reviews.freebsd.org/D52067