MAINTAINERS: add patterns to DELL WMI EXTRAS

Signed-off-by: Joe Perches <joe@perches.com>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/MAINTAINERS b/MAINTAINERS
index f40a2a2..9913823 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1892,6 +1892,7 @@
 DELL WMI EXTRAS DRIVER
 M:	Matthew Garrett <mjg59@srcf.ucam.org>
 S:	Maintained
+F:	drivers/platform/x86/dell-wmi.c
 
 DEVICE NUMBER REGISTRY
 M:	Torben Mathiasen <device@lanana.org>