ARM: OMAP4: TWL: mux sys_drm_msecure as output for PMIC

On OMAP4 boards using the TWL6030 PMIC, the sys_drm_msecure is
connected to the MSECURE input of the TWL6030 PMIC.  This signal
controls the secure-mode operation of the PMIC.  If its not mux'd
correctly, some functionality of the PMIC will not be accessible since
the PMIC will be in secure mode.

For example, if the TWL RTC is in secure mode, most of its registers
are read-only, meaning (re)programming the RTC (e.g. for wakeup from
suspend) will fail.

To fix, ensure the signal is properly mux'd as output when TWL is
intialized.

This fix is required when using recent versions of u-boot (>= v2012.04.01)
since u-boot is no longer setting the default mux for this pin.

Signed-off-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>