common: dma-mapping: add support for generic dma_mmap_* calls

Commit 9adc5374 ('common: dma-mapping: introduce mmap method') added a
generic method for implementing mmap user call to dma_map_ops structure.

This patch converts ARM and PowerPC architectures (the only providers of
dma_mmap_coherent/dma_mmap_writecombine calls) to use this generic
dma_map_ops based call and adds a generic cross architecture
definition for dma_mmap_attrs, dma_mmap_coherent, dma_mmap_writecombine
functions.

The generic mmap virt_to_page-based fallback implementation is provided for
architectures which don't provide their own implementation for mmap method.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Kyungmin Park <kyungmin.park@samsung.com>
diff --git a/include/asm-generic/dma-coherent.h b/include/asm-generic/dma-coherent.h
index abfb268..2be8a2d 100644
--- a/include/asm-generic/dma-coherent.h
+++ b/include/asm-generic/dma-coherent.h
@@ -29,6 +29,7 @@
 #else
 #define dma_alloc_from_coherent(dev, size, handle, ret) (0)
 #define dma_release_from_coherent(dev, order, vaddr) (0)
+#define dma_mmap_from_coherent(dev, vma, vaddr, order, ret) (0)
 #endif
 
 #endif