msm: footswitch: Allow assigning of consumer names to footswitches

regulator_get() expects two arguments: a consumer device pointer and
a regulator name.  For footswitch regulators, users of this API have
usually passed NULL in place of the device pointer, which was treated
like a wildcard for the purposes of matching. Those that passed
pointers received no advantage from it anyway, since it was not
possible to specify consumer device names in the devices-* files using
the macros in footswitch.h.

Improve on this by expanding the footswitch macros to take a consumer
name strings. This allows regulator_get() to find matches using a
stricter criteria that considers the consumer device name and ID,
as well as the regulator name.

Change-Id: I77618007b674480aff031329757b41cc00014478
Signed-off-by: Matt Wagantall <mattw@codeaurora.org>