ARM: OMAP2+: dm81xx: Add clkdm and hwmod for SATA

Add the SATA clockdomain (part of CM_DEFAULT) and a hwmod for the SATA
block on dm81xx.

Tested on DM8168 EVM.

Signed-off-by: Kevin Hilman <khilman@baylibre.com>
[Bartosz: removed an unused define]
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>