ARM: highbank: select ARCH_DMA_ADDR_T_64BIT for LPAE

ECX-2000 has some 64-bit capable DMA and therefore needs dma_addr_t
to be a 64-bit size.
Signed-off-by: Rob Herring <rob.herring@calxeda.com>

arch/arm/mach-highbank/Kconfig

 config ARCH_HIGHBANK
 	bool "Calxeda ECX-1000/2000 (Highbank/Midway)" if ARCH_MULTI_V7
+	select ARCH_DMA_ADDR_T_64BIT if ARM_LPAE
 	select ARCH_HAS_CPUFREQ
 	select ARCH_HAS_HOLES_MEMORYMODEL
 	select ARCH_HAS_OPP