The unsigned long datatype is not sufficient for mapping physical addresses
>= 4GB.

This patch ensures that the phys_addr_t datatype is used to represent
the start address of a membank, which may reside above the 4GB boundary.
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>