Test: mpp_test

Usage: ./mpp_test.sh [-n | --nominal] [(-v | --verbosity) <verbosity>]

Description:
This test tests basic multi-purpose pin (MPP) functionality.

For 7x27, 7x30, and 8x50 targets, this unit test tests if one MPP can be set
as a digital output successfully.

For 8660, this test is more limited because the MPP drivers used on 8660 do not
expose control to userspace.  All that can be observed is the debug output of
the MPP drivers that is printed via the dbg_show callback in the GPIO driver.
Thus reading <debugfs>/gpio will allow one to find out the configuration and
current state of all MPPs.

This unit test therefore checks to see if there is the correct number of PMIC
8058 MPPs listed in <debugfs>/gpio and that each has an allowed type.

Targets: 8660, 7x27, 7x30, 8x50

Notes:
(1) On Android adb shell, busybox installation is required for test to run.
(2) On Android adb shell, debugfs must be mounted at $ANDROID_DATA/debug
