efi: Remove Matthew Garrett as efivarfs maintainer

Matthew Garrett is still listed as a efivarfs co-maintainer, but the
email address bounces, and Matt is no longer involved in maintaining
this code.

So let's remove Matt as a efivarfs co-maintainer from MAINTAINERS.
Thanks for all the hard work!

Acked-by: Matthew Garrett <[email protected]>
Signed-off-by: Ard Biesheuvel <[email protected]>

Author: ardbiesheuvel

MAINTAINERS

@@ -7616,7 +7616,6 @@ S:	Maintained
 F:	drivers/firmware/efi/test/
 
 EFI VARIABLE FILESYSTEM
-M:	Matthew Garrett <[email protected]>
 M:	Jeremy Kerr <[email protected]>
 M:	Ard Biesheuvel <[email protected]>
 L:	[email protected]