[ARM] 3605/1: AT91RM9200 Power Management

Patch from Andrew Victor

This patch adds the core Power Management support for the AT91RM9200
processor.  It will support suspend-to-RAM and standby modes.

The suspend-to-RAM functionality is not 100% complete.  The code that
needs to be execute from the internal SRAM to restore the system is
outstanding.  For now we just fall through to Standby mode.

The AT91-specific at91_suspend_entering_slow_clock() function will
eventually be replaced by clk_must_disable() once that functionality is
added to mainline clock API.

Patch from David Brownell.

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