get_maintainer: it's '--pattern-depth', not '-pattern-depth'

Though it appears that Perl's GetOptions will take either, the latter is
not documented in the options listing.

Cherry picked from Linux commit cc7ff0ef6eca3deeea4a424ca47a67c8450d5424.
Signed-off-by: NBrian Norris <computersforpeace@gmail.com>
Reviewed-by: NThomas Huth <thuth@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

scripts/get_maintainer.pl

@@ -748,7 +748,7 @@ Other options:
   --help => show this help information
 
 Default options:
-  [--email --nogit --git-fallback --m --n --l --multiline -pattern-depth=0
+  [--email --nogit --git-fallback --m --n --l --multiline --pattern-depth=0
    --remove-duplicates --rolestats]
 
 Notes: