Remove GPIO hog for modem power, as well as define userspace GPIO
switches for enabling and resetting the modem. While at that, define a
switch for the external GPIO available on the power connector.
Signed-off-by: Lech Perczak <lech.perczak@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/17503
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>