parisc: Provide dummy dma_mmap_coherent() and dma_get_sgtable()

parisc/allmodconfig:

drivers/media/v4l2-core/videobuf2-dma-contig.c: In function ‘vb2_dc_mmap’:
drivers/media/v4l2-core/videobuf2-dma-contig.c:204: error: implicit declaration of function ‘dma_mmap_coherent’
drivers/media/v4l2-core/videobuf2-dma-contig.c: In function ‘vb2_dc_get_base_sgt’:
drivers/media/v4l2-core/videobuf2-dma-contig.c:387: error: implicit declaration of function ‘dma_get_sgtable’

For architectures using dma_map_ops, dma_mmap_coherent() and
dma_get_sgtable() are provided in <asm-generic/dma-mapping-common.h>.

Parisc does not use dma_map_ops, hence it should implement them itself.
For now, use dummy implementations that just return -EINVAL, until the
API has been finalized, as it cannot be supported on PA-RISC as-is.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: James Bottomley <James.Bottomley@hansenpartnership.com>
Cc: linux-parisc@vger.kernel.org
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>

arch/parisc/include/asm/dma-mapping.h

@@ -238,4 +238,19 @@ void * sba_get_iommu(struct parisc_device *dev);
 /* At the moment, we panic on error for IOMMU resource exaustion */
 #define dma_mapping_error(dev, x)	0
 
+/* This API cannot be supported on PA-RISC */
+static inline int dma_mmap_coherent(struct device *dev,
+				    struct vm_area_struct *vma, void *cpu_addr,
+				    dma_addr_t dma_addr, size_t size)
+{
+	return -EINVAL;
+}
+
+static inline int dma_get_sgtable(struct device *dev, struct sg_table *sgt,
+				  void *cpu_addr, dma_addr_t dma_addr,
+				  size_t size)
+{
+	return -EINVAL;
+}
+
 #endif