msm: mdm: Add mdm2 driver.

This is a re-organized version of the charm driver.
Instead of hardcoding the gpio values, they are now passed
in via platform resources. Also, functions that are common
between the old and new drivers are separated out into
a common file.

Change-Id: Iaafeb27a6056a3cb6572410c08e7f31fae117662
Signed-off-by: Joel King <joelking@codeaurora.org>