[PATCH] dmaengine: shdma: fix a build failure on platforms with no DMA support

[Guennadi Liakhovetski]

On platforms with no support for the shdma dmaengine driver build is
currently failing with

drivers/built-in.o: In function `sh_mobile_sdhi_probe':
drivers/mmc/host/sh_mobile_sdhi.c:170: undefined reference to`shdma_chan_filter'

Fix the breakage by defining shdma_chan_filter to NULL in such
configurations.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski+renesas at gmail.com>
---

This is for "next." Compile-tested only. I'll test it on hardware next 
week, but I don't think it shall break anything.

 include/linux/sh_dma.h |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/include/linux/sh_dma.h b/include/linux/sh_dma.h
index b64d6be..1fd8a20 100644
--- a/include/linux/sh_dma.h
+++ b/include/linux/sh_dma.h
@@ -99,6 +99,10 @@ struct sh_dmae_pdata {
 #define CHCR_TE	0x00000002
 #define CHCR_IE	0x00000004
 
+#if IS_ENABLED(CONFIG_SH_DMAE)
 bool shdma_chan_filter(struct dma_chan *chan, void *arg);
+#else
+#define shdma_chan_filter NULL
+#endif
 
 #endif
-- 
1.7.2.5