[ARM] 4207/1: defconfig fixes, use RTC_DRV_AT91RM9200

When "rtc-at91" was renamed to "rtc-at91rm9200" not all the relevant
defconfig entries were updated.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>