ARM: OMAP2+: PRCM and hwmod changes for v4.3

This series adds:

- I/O wakeup support for AM43xx
- register lock and unlock support to the hwmod code (needed for the RTC
  IP blocks on some chips)
- several fixes for sparse warnings and an unnecessary null pointer test
- a DRA7xx clockdomain configuration workaround, to deal with some hardware

Basic build, boot, and PM tests are here:

Since I do not have an AM43xx or DRA7xx device, I can't test on those
Merge branch 'prcm-a-for-v4.3' into hwmod-prcm-for-v4.3