arm/dt: Add gpio devices for Qualcomm PMIC 8941

Add the PMIC gpio devices into the pm8941 specific Device Tree
include file. Also add a board specific include file which is
used to override gpio configuration parameters.

By default the devices are disabled in the pm8941 specific
include, so they must be explicitly enabled in the board
specific file. This is done so that particular boards can choose
not to add a gpio to the configuration.

Defaults for the copper board are also added. PMIC gpios 25-36
are specified with a 'out_strength' of 1 since the current
hardware does not initialize them properly.

Change-Id: If393f74cdb039064216d0254352f56d90f6be0f7
Signed-off-by: Michael Bohan <mbohan@codeaurora.org>