ARM: dts: OMAP2+: Add SDMA controller bindings and nodes

Add SDMA controller binding for OMAP2+ devices and populate DMA client
information for SPI and MMC peripheral on OMAP3+ devices. Please note
that OMAP24xx devices do not have SPI and MMC bindings available yet and
so DMA client information is not populated.

Signed-off-by: Jon Hunter <jon-hunter@ti.com>
Reviewed-by: Felipe Balbi <balbi@ti.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Tested-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Benoit Cousson <benoit.cousson@linaro.org>