avr32: Add hardware power-down function call

This patch adds in the indirect call to pm_power_off(), as is done in
other architectures (e.g. ARM).

Tested on NGW100, with custom board with GPIO control over main DC
power.

Signed-off-by: Peter Ma <pma@mediamatech.com>
Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
diff --git a/arch/avr32/kernel/process.c b/arch/avr32/kernel/process.c
index 3de1154..6cf9df1 100644
--- a/arch/avr32/kernel/process.c
+++ b/arch/avr32/kernel/process.c
@@ -54,6 +54,8 @@
 
 void machine_power_off(void)
 {
+	if (pm_power_off)
+		pm_power_off();
 }
 
 void machine_restart(char *cmd)