ARM: at91: pm: fallback to slowclock when backup mode fails

If the backup sram allocation fails, ensure we can suspend by falling back
to the usual slow clock mode.

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Wenyou Yang <wenyou.yang@atmel.com>
diff --git a/arch/arm/mach-at91/pm.c b/arch/arm/mach-at91/pm.c
index ef9c1d2..fc40264 100644
--- a/arch/arm/mach-at91/pm.c
+++ b/arch/arm/mach-at91/pm.c
@@ -544,6 +544,11 @@
 securam_fail:
 	iounmap(pm_data.sfrbu);
 	pm_data.sfrbu = NULL;
+
+	if (pm_data.standby_mode == AT91_PM_BACKUP)
+		pm_data.standby_mode = AT91_PM_SLOW_CLOCK;
+	if (pm_data.suspend_mode == AT91_PM_BACKUP)
+		pm_data.suspend_mode = AT91_PM_SLOW_CLOCK;
 }
 
 struct pmc_info {