extcon: add MAX14526 MUIC support

MAX14526 is a powerful extcon chip which allows detection of various
plugs like usb, mhl, uart, headset etc. This version of driver
implements support of AP-usb and CP-usb/uart paths.

Tested-by: Andreas Westman Dorcsak <hedmoo@yahoo.com> # LG P880 T30
Tested-by: Svyatoslav Ryhel <clamor95@gmail.com> # LG P895 T30
Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>