Add amf_return return code everywhere

steps/30-formatting.step

@@ -26,3 +26,5 @@ echo "~> Mount partitions"
 mount $rootformat /mnt
 mkdir -p /mnt/boot
 mount ${blockdevice}1 /mnt/boot
+
+amf_return=0

steps/40-install.step

@@ -2,3 +2,5 @@
 
 echo "~> Installing 'base' group and 'grub', 'efibootmgr'"
 pacstrap /mnt base grub efibootmgr
+
+amf_return=0

steps/50-configure.step

@@ -33,3 +33,5 @@ echo "HOOKS=\"base udev autodetect modconf block keyboard keymap encrypt filesys
 
 echo "~> ... and recompile the kernel"
 arch-chroot /mnt mkinitcpio -p linux
+
+amf_return=0