ARM: mach-integrator: Add stub for pci_v3_early_init() for !CONFIG_PCI

This fixes a compile error where CONFIG_PCI is disabled:

  LD      init/built-in.o
arch/arm/mach-integrator/built-in.o: In function `ap_map_io':
integrator_cp.c:(.init.text+0x570): undefined reference to `pci_v3_early_init'
make[1]: *** [vmlinux] Error 1
make: *** [sub-make] Error 2

Cc: stable@vger.kernel.org
Signed-off-by: Joerg Roedel <joro@8bytes.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Olof Johansson <olof@lixom.net>