ARM: 7058/1: LPAE: Cast the dma_addr_t argument to unsigned long in dma_to_virt

This is to avoid a compiler warning when invoking the __bus_to_virt()
macro. The dma_to_virt() function gets addresses within the 32-bit
range.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>