checkpatch: add sub routine get_stat_real()

checkpatch currently contains duplicate code.  We can define a sub
routine and call that instead.  This reduces code duplication and line
count.

Add subroutine get_stat_real()

Link: http://lkml.kernel.org/r/1519700648-23108-2-git-send-email-me@tobin.cc
Signed-off-by: Tobin C. Harding <me@tobin.cc>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>