dma: sh/shdma-base.c: remove unnecessary null pointer check

the variable chan is dereferenced in line 635, so it is no reason to check
null again in line 641.

Signed-off-by: Cong Ding <dinggnu@gmail.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
1 file changed