X86: integrate CMA with DMA-mapping subsystem

This patch adds support for CMA to dma-mapping subsystem for x86
architecture that uses common pci-dma/pci-nommu implementation. This
allows to test CMA on KVM/QEMU and a lot of common x86 boxes.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
CC: Michal Nazarewicz <mina86@mina86.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index c9866b0..7cbdfda 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -31,6 +31,7 @@
 	select ARCH_WANT_OPTIONAL_GPIOLIB
 	select ARCH_WANT_FRAME_POINTERS
 	select HAVE_DMA_ATTRS
+	select HAVE_DMA_CONTIGUOUS if !SWIOTLB
 	select HAVE_KRETPROBES
 	select HAVE_OPTPROBES
 	select HAVE_FTRACE_MCOUNT_RECORD