msm: dma: add 7x30 security domain abstraction

The MSM SOC's DMA controller contains several security domains.
On the MSM7x00, only security domain 3 is accessible to our CPU.
The 7x30, however, uses security domain 2.  Fix up the register
definition macros to select this appropriately, based on
configured target.

Signed-off-by: Daniel Walker <dwalker@codeaurora.org>
Signed-off-by: David Brown <davidb@codeaurora.org>
Signed-off-by: Gregory Bean <gbean@codeaurora.org>
Signed-off-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>
Signed-off-by: Stepan Moskovchenko <stepanm@codeaurora.org>