ARM: mach-shmobile: Enable DMAEngine for SDHI on AG5EVM

Add SDHI0 and SDHI1 slave ids for RX and TX to enable
DMA Engine support for SDHI on the AG5EVM board.

Signed-off-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>