test/inhfd: remove redundant mnt_id initialization

Remove C-style pre-initialization of mnt_id to -1. The
variable is always assigned inside the loop, and the for/else
construct raises an exception if it is never set.

Assisted-by: Claude Code (claude-opus-4-6)
Signed-off-by: Adrian Reber <areber@redhat.com>

test/inhfd/fifo.py

@@ -15,7 +15,6 @@ def create_fds():
     os.system("umount -l %s" % tdir)
     os.rmdir(tdir)
 
-    mnt_id = -1
     with open("/proc/self/fdinfo/%d" % fd1.fileno()) as f:
         for line in f:
             line = line.split()