msm: mdm: setup vddmin gpios for external modem

One gpio is used by rpm on the the apq8064 to wakeup
the external modem and the other is used to monitor
vddmin transitions on the external modem.

Change-Id: I5b6ddeac47c0c1bf5c3ac07a014a22804a49c5cf
Signed-off-by: Joel King <joelking@codeaurora.org>