The current OMAP2 SHAM support doesn't enable DMA
so add that support so it can use DMA just like OMAP3.

CC: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
[paul@pwsan.com: fixed lines causing sparse warnings]
Signed-off-by: Paul Walmsley <paul@pwsan.com>