dma: select GENERIC_ALLOCATOR for DMA_REMAP

When DMA_REMAP is enabled, code in remap.c needs generic allocator.
It currently worked since few architectures uses it (arm64, csky) and
they both select GENERIC_ALLOCATOR. Select it when using DMA_REMAP
to have correct dependencies.
Signed-off-by: Clement Leger <clement.leger@kalray.eu>
Signed-off-by: Christoph Hellwig <hch@lst.de>

kernel/dma/Kconfig

@@ -57,6 +57,7 @@ config SWIOTLB
 
 config DMA_REMAP
 	depends on MMU
+	select GENERIC_ALLOCATOR
 	bool
 
 config DMA_DIRECT_REMAP