[ARM] 5441/1: Use pr_err on error paths in at91 pm

Change pr_debug to pr_err on error paths in the AT91 power management
code. All of the errors will result in the cpu not going into the
suspend state. This patch makes it possible to identify problems with
suspend when power management debugging is not enabled.

Signed-off-by: Ryan Mallon <ryan@bluewatersys.com>
Acked-by: Andrew Victor <linux@maxim.org.za>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>