thingino-motors: fix S59motor stop path wedging motors-daemon

[catongates]

Fixes #1510.

What's wrong

S59motor's stop_daemon could never actually kill motors-daemon: the daemon self-daemonizes under -d (double-fork + setsid), so the PID start-stop-daemon -m records is the intermediate child, which exits immediately — the pidfile is stale from the moment it is written. stop() didn't check the result and ran rmmod motor anyway, which succeeds against the still-live daemon because motor_fops lacks .owner = THIS_MODULE (module use count stays 0 with a live opener — filed separately as themactep/ingenic-sdk#45). That leaves motors-daemon in permanently uninterruptible D state, immune to SIGKILL, recoverable only by a power cycle.

Full detail and live reproduction in #1510.

What this changes

• stop_daemon now matches the real process (anchored on the binary path — an unanchored pkill -f pattern also matches the invoking shell) and escalates SIGTERM → SIGKILL with a bounded wait, returning a real status.
• stop() now refuses to rmmod unless the daemon is confirmed gone, turning the failure mode from an unrecoverable wedge into an ordinary loud error.

Both changes are scoped to stop_daemon()/stop(); nothing else in the file is touched.

Testing

Live on an Eufy E220 (T8410C, T31X, ciao+f433166): the exact S59motor restart that previously wedged the daemon now completes cleanly, with the daemon healthy afterward and motors -j responsive. Reproduced (and now fixed) on both motion_driver: legacy and profiled, so this is unrelated to the acceleration settings, which were the original — wrong — suspect.

# /etc/init.d/S59motor restart
Stopping motors
Setting up motors
Set GPIO per motor phase
Load motor module with parameters: hmaxstep=4100 vmaxstep=1150 ...
Home motors
Move to 2050,450
# ps w | grep motors-daemon
30645 root      1132 S    /usr/bin/motors-daemon -d -p
# motors -j
{"status":"0","xpos":"2050","ypos":"450","speed":"900","invert":"0"}

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Investigated, tested, and drafted by an AI assistant while looking into PTZ motion behavior on this camera.