Refactor: tools: Drop crm_diff.c:strip_patch_cib_version()

This function never validated format. It had two cases: format == 2, and
format != 2. The format != 2 case assumed format == 1.

The format == 2 case can be converted to a one-liner.

Signed-off-by: Reid Wahl <nrwahl@protonmail.com>