sm8250-common: remove OMX

* OMX HW video codecs are no longer used after enabling Codec2
 * OMX HW audio codecs won't work without QCOM A/V enhancements, which
   we don't have on Lineage.

proprietary/vendor/etc/seccomp_policy/mediacodec.policy

@@ -1,22 +0,0 @@
-# device specific syscalls
-# extension of services/mediacodec/minijail/seccomp_policy/mediacodec-seccomp-arm.policy
-pselect6: 1
-eventfd2: 1
-sendto: 1
-recvfrom: 1
-_llseek: 1
-sysinfo: 1
-getcwd: 1
-getdents64: 1
-ARM_cacheflush: 1
-inotify_init1: 1
-inotify_add_watch: 1
-inotify_rm_watch: 1
-uname: 1
-ueventd: 1
-timer_create: 1
-timer_settime: 1
-rt_sigtimedwait: 1
-readlink: 1
-open: 1
-sched_setaffinity: 1