ueventd.qcom.rc: Change /dev/diag owner permission to system

Recently the owner permission of /dev/diag was changed away
from system. This broke the mode reset functionality. Change
the owner permission back to system on /dev/diag

Change-Id: Ia6c28f0d147ed16a399202a8e0fa043b27dc7712
Merge "ueventd.qcom.rc: Change /dev/diag owner permission to system"