sh: fix build warning in board-sh7757lcr

This patch fixed the following build warnings:

  CC      arch/sh/boards/board-sh7757lcr.o
arch/sh/boards/board-sh7757lcr.c:77: warning: initialization from incompatible pointer type
arch/sh/boards/board-sh7757lcr.c:106: warning: initialization from incompatible pointer type
arch/sh/boards/board-sh7757lcr.c:151: warning: initialization from incompatible pointer type
arch/sh/boards/board-sh7757lcr.c:181: warning: initialization from incompatible pointer type
arch/sh/boards/board-sh7757lcr.c:213: warning: missing braces around initializer
arch/sh/boards/board-sh7757lcr.c:213: warning: (near initialization for ‘sh7757lcr_mmcif_dma.chan_priv_tx’)

Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>