ARM: shmobile: sh73a0: bugfix: SY-DMAC number

681e1b3e
(ARM: mach-shmobile: sh73a0 DMA Engine support for SY-DMAC)
adds SY-DMAC, but it is 218, not 318

This patch is based on v2.0 manual

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Acked-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>