kmod-{omnia,mox}: remove dropped kmod-letrig-* packages

Removes:
* kmod-ledtrig-default-on
* kmod-ledtrig-heartbeat
* kmod-ledtrig-netdev
* kmod-ledtrig-timer

Based on upstream change https://github.com/openwrt/openwrt/commit/583e39e3d5149357c8070eb7cdd942e42ea44906
Fixes: a16311e826ac1315b3f7a29b7034da5deda32cf6 ("essential_packages: drop package kmod-ledtrig-heartbeat")
3 jobs for hbd/changes in 14 seconds (queued for 4 seconds)
Status Name Job ID Coverage
  Build
passed build #571478

00:00:06

 
  Check
passed lint #571479

00:00:07

passed test #571480

00:00:07