ARM: OMAP2+: hwmod: Add API to enable IO ring wakeup

ARM: OMAP2+: hwmod: Add API to enable IO ring wakeup

Add API to enable IO pad wakeup capability based on mux pad and
wake_up enable flag available from hwmod_mux initialization.

Use the wakeup_enable flag and enable wakeup capability for the given
pads. Wakeup capability will be enabled/disabled during hwmod idle
transition based on whether wakeup_flag is set or cleared.  If the
hwmod is currently idled, and any mux values were changed by
_set_idle_ioring_wakeup(), the SCM PADCTRL registers will be updated.

Signed-off-by: Govindraj.R <govindraj.raja@ti.com>
Signed-off-by: Tero Kristo <t-kristo@ti.com>
Tested-by: Kevin Hilman <khilman@ti.com>
Reviewed-by: Kevin Hilman <khilman@ti.com>
[paul@pwsan.com: rearranged code to limit indentation; cleaned up
 function documentation; removed unused non-static functions; modified
 to search all hwmod pads, not just dynamic remuxing ones; modified to
 update SCM regs if hwmod is currently idle and any pads have changed]
Signed-off-by: Paul Walmsley <paul@pwsan.com>