dmaengine: nbpf_error_get_channel() can be static

CC: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
CC: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

drivers/dma/nbpfaxi.c

@@ -351,7 +351,7 @@ static u32 nbpf_error_get(struct nbpf_device *nbpf)
 	return nbpf_read(nbpf, NBPF_DSTAT_ER);
 }
 
-struct nbpf_channel *nbpf_error_get_channel(struct nbpf_device *nbpf, u32 error)
+static struct nbpf_channel *nbpf_error_get_channel(struct nbpf_device *nbpf, u32 error)
 {
 	return nbpf->chan + __ffs(error);
 }