[ARM] 3951/1: AT91: Rename user peripheral header files

Most of the AT91RM9200 user peripherals are also integrated into the
Atmel SAM9 range of processors.  This patch renames the headers from
at91rm9200_xx.h to at91_xx.h to indicate they're not
at91rm9200-specific.

The new SAM9-specific registers and register bits have also been
defined.

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