x86: unify pci-nommu

merge pci-base_32.c and pci-nommu_64.c into pci-nommu.c
Their code were made the same, so now they can be merged.

Signed-off-by: Glauber Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>