asm-generic: Add new pci.h and use it

The asm/pci.h used for many newer architectures share similar definitions.
Move the common parts to asm-generic/pci.h to allow for sharing code.

Suggested-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/lkml/CAK8P3a0JmPeczfmMBE__vn=Jbvf=nkbpVaZCycyv40pZNCJJXQ@mail.gmail.com/
Link: https://lore.kernel.org/r/20220722214944.831438-5-shorne@gmail.com


Signed-off-by: Stafford Horne <shorne@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Pierre Morel <pmorel@linux.ibm.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>