ARM: relax conditions required for enabling Contiguous Memory Allocator

Contiguous Memory Allocator requires only paging and MMU enabled not
particular CPU architectures, so there is no need for strict dependency
on CPU type. This enables to use CMA on some older ARM v5 systems which
also might need large contiguous blocks for the multimedia processing hw
modules.
Reported-by: Prabhakar Lad <prabhakar.lad@ti.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Prabhakar Lad <prabhakar.lad@ti.com>

arch/arm/Kconfig

@@ -6,7 +6,7 @@ config ARM
 	select HAVE_DMA_API_DEBUG
 	select HAVE_IDE if PCI || ISA || PCMCIA
 	select HAVE_DMA_ATTRS
-	select HAVE_DMA_CONTIGUOUS if (CPU_V6 || CPU_V6K || CPU_V7)
+	select HAVE_DMA_CONTIGUOUS if MMU
 	select HAVE_MEMBLOCK
 	select RTC_LIB
 	select SYS_SUPPORTS_APM_EMULATION