maintainers: Fix PS3 patterns

Correct the MAINTAINERS file patterns for PS3.  Removes some PS3
patterns that were under 'CELL BROADBAND ENGINE ARCHITECTURE', and
adds missing PS3 sound and RTC driver patterns.

CC: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Geoff Levand <geoffrey.levand@am.sony.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>