MAINTAINERS: fix reference to moved drivers/{misc => auxdisplay}/panel.c

Commit 51c1e9b ("auxdisplay: Move panel.c to drivers/auxdisplay folder")
moved the file, but the MAINTAINERS reference was not updated.

Link: https://lore.kernel.org/lkml/20180928220131.31075-1-joe@perches.com/
Reported-by: Joe Perches <joe@perches.com>
Signed-off-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>

MAINTAINERS

@@ -10949,7 +10949,7 @@ M:	Willy Tarreau <willy@haproxy.com>
 M:	Ksenija Stanojevic <ksenija.stanojevic@gmail.com>
 S:	Odd Fixes
 F:	Documentation/auxdisplay/lcd-panel-cgram.txt
-F:	drivers/misc/panel.c
+F:	drivers/auxdisplay/panel.c
 
 PARALLEL PORT SUBSYSTEM
 M:	Sudip Mukherjee <sudipm.mukherjee@gmail.com>