usb: Enable midi function in charger mode

It needs a USB function in charger mode to set the charging current to
500mA/900mA.

Bug: 188744218
Test: charging at 900mA in charger mode
Signed-off-by: Kyle Tso <kyletso@google.com>
Change-Id: I95c98ecec30dd4394228f7290412c303771a3158
1 file changed