build: remove localversion-rt from git tree

Merge Request Required Information

Summary of Changes

When we were pulling RT as an out-of-tree set of patches, we used the localversion-rt file to add the RT identifying data in the uname output. Now that RT has merged upstream we do not need to track this.

Note that the kernel specfile removes this file unconditionally in the %build section so that it does not affect the uname -r output.

This mainly affects kernel developers who are building trees locally.

Approved Development Ticket(s)

Resolves: RHEL-73163

JIRA: https://issues.redhat.com/browse/RHEL-73163

Upstream Status: RHEL only

Signed-off-by: Clark Williams williams@redhat.com