The sg list used to prepare cyclic DMA descriptors is currently
allocated statically on the stack as an array of 32 elements. This makes
the shdma_prep_dma_cyclic() function consume a lot of stack space, as
reported by the compiler:

drivers/dma/sh/shdma-base.c: In function ‘shdma_prep_dma_cyclic’:
drivers/dma/sh/shdma-base.c:715:1: warning: the frame size of 1056 bytes
is larger than 1024 bytes [-Wframe-larger-than=]

Given the limited Linux kernel stack size, this could lead to stack
overflows. Fix the problem by allocating the sg list dynamically.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>