[ARM] 4754/1: [AT91] SSC library support

Core support of the Atmel SSC library for all Atmel AT91 processors.

Based on David Brownell's initial patch for the AT91RM9200.

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