ARM/dt: hammerhead: Reduce minimum panel brightness

Default minimum brightness is a tad too high, this change makes reading
in a dark environment much more enjoyable. A value of 3 is still within
the valid range (see lm3630 blmap).

Change-Id: I40f690e7a06459a06db939c37108bae6fc9c52d6
hammerhead kernel: implement always on rgb led support

When offms is set to 0, configure a single point
duty cycle at the desired led brightness.

Change-Id: I93b61af52ee2f695035e7f5d78814251c8d1da8d
ARM: Use -mcpu=cortex-a15 when targeting MSM Krait CPUs

Enable compiler optimizations specific to the Cortex-A15
processor when targeting MSM Krait CPUs. This is necessary
take advantage of the UDIV/SDIV instructions supported by
these processors. To accomplish this, we need to remove the
-march=armv7-a ISA restriction from the compiler options
because 'cortex-a15' is a superset of 'armv7-a'.

Change-Id: I6215aecc11fb4f77c971de7b84f68649ef234357
Signed-off-by: Stepan Moskovchenko <stepanm@codeaurora.org>