MAINTAINERS: assign lib/charset.c

lib/charset.c is only used by the EFI subsystem.
Signed-off-by: NHeinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: NAlexander Graf <agraf@suse.de>

MAINTAINERS

@@ -368,6 +368,7 @@ F:	doc/README.iscsi
 F:	include/efi*
 F:	include/pe.h
 F:	include/asm-generic/pe.h
+F:	lib/charset.c
 F:	lib/efi*/
 F:	test/py/tests/test_efi*
 F:	cmd/bootefi.c