ARM: kconfig: allow PCI support to be selected with ARCH_MULTIPLATFORM

ARM: kconfig: allow PCI support to be selected with ARCH_MULTIPLATFORM

When targetting ARCH_MULTIPLATFORM, we may include support for SoCs with
PCI-capable devices (e.g. mach-virt with virtio-pci).

This patch allows PCI support to be selected for these SoCs by selecting
CONFIG_MIGHT_HAVE_PCI when CONFIG_ARCH_MULTIPLATFORM=y and removes the
individual selections from multi-platform enabled SoCs.

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Olof Johansson <olof@lixom.net>
(cherry picked from commit 08d38bebb4dcd6414944f8277ea5ea30010664fe)
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Conflicts:
	arch/arm/mach-bcm/Kconfig
	arch/arm/mach-cns3xxx/Kconfig
	arch/arm/mach-imx/Kconfig