LinuxKPI: PCI: add counter for linux_dma_map_phys_common() errors

LinuxKPI is asking for single-segment mappings. Some (wireless) drivers
are using this to map multi-pages and our busdma framework is not very
friendly to that as single-segments [D31823]. Add a counter so we can
track when this happens to gather more information.

Sponsored by: The FreeBSD Foundation
Reviewed by: hselasky
MFC after: 3 days
Differential Revision: https://reviews.freebsd.org/D34715