MAINTAINERS: update DMA BUFFER SHARING patterns

One pattern per F: line please...

Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>