ARM: stop *MIGHT_HAVE_PCI* config from being selected redundantly

*MIGHT_HAVE_PCI* config is already selected in ARCH_MULTIPLATFORM.
Don't select it redundantly in all ARCH_MULTIPLATFORM based machines.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>