km/scripts: fix ramfs

'actual_bank' is not used anymore, instead boot_bank is used.

Signed-off-by: Andreas Huber <andreas.huber@keymile.com>

board/keymile/scripts/ramfs-common.txt

@@ -1,5 +1,5 @@
 addramfs=setenv bootargs "${bootargs} phram.phram=rootfs${boot_bank},${rootfsaddr},${rootfssize}"
-actual_bank=-1
+boot_bank=-1
 altbootcmd=run ${subbootcmds}
 bootcmd=run ${subbootcmds}
 subbootcmds=tftpfdt tftpkernel setrootfsaddr tftpramfs flashargs add_default addpanic addramfs boot