MAINTAINERS: add quotation marks around names with periods

This makes it easier to copy/paste names with periods to email clients.

All the other names with periods already have quotation marks.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>