Completes the #227 PTZ env rename (majestic-webui#232, firmware#2341) in
the last place still writing the old name: the three customizer.sh files
carrying 'fw_setenv gpio_motors ...' now write ptz_gpio instead. The
gpio-motors utility reads ptz_gpio first and falls back to gpio_motors
since firmware#2341, and it is the only consumer of the variable anywhere
in the org, so the rename is mechanical.
Each device also gains 'fw_setenv ptz_control gpio' — not part of the
rename, but required by it: the WebUI dropped its auto-detection from a
bare pin list (unset ptz_control now means no PTZ, per flyrouter's ruling
on the same issue; majestic-webui#255). Without the method named, these
devices would keep their motors but lose their pads. In
t23_lite_jooan-a6m-u the pin line was commented out, so both new lines
are commented there too.
