[ARM] 3586/1: AT91RM9200 header update

Patch from Andrew Victor

Added definition for the bits in the Chip ID register.
Corrected the capitalization of AT91_RTC_AMPM register name.

Signed-off-by: Andrew Victor <andrew@sanpeople.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>