MAINTAINERS: update brcm gpio filename pattern

Commit 23a71fd616bf ("dt-bindings: brcm: rationalize Broadcom
documentation naming") renamed the file, update the pattern.

Signed-off-by: Joe Perches <[email protected]>
Acked-by: Scott Branden <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
1 file changed