arm64: fix build error if DMA_CMA is enabled

arm64/include/asm/dma-contiguous.h is trying to include
<asm-genric/dma-contiguous.h> which does not exist, and thus failing
build for arm64 if we enable CONFIG_DMA_CMA. This patch fixes build
error by removing unwanted header inclusion from arm64's dma-contiguous.h.
Signed-off-by: Pankaj Dubey <pankaj.dubey@samsung.com>
Signed-off-by: Somraj Mani <somraj.mani@samsung.com>
Acked-by: Laura Abbott <lauraa@codeaurora.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/include/asm/dma-contiguous.h

@@ -18,7 +18,6 @@
 #ifdef CONFIG_DMA_CMA
 
 #include <linux/types.h>
-#include <asm-generic/dma-contiguous.h>
 
 static inline void
 dma_contiguous_early_fixup(phys_addr_t base, unsigned long size) { }