mvebu: fix partition type and signature for sdcard

Previously the partition signature was assigned from provided type. Now
both are corrected wherein signature is always generated from
SOURCE_DATE_EPOCH. With that the root file system can be identified
by PARTUUID string, without relying on static declaration of device node.
This commit also does some cosmetics, removing trailing whitespace and
replacing spaces with tab.

Signed-off-by: Tomasz Maciej Nowak <tomek_n@o2.pl>

target/linux/mvebu/image/Makefile

@@ -13,8 +13,10 @@ include $(INCLUDE_DIR)/image.mk
 
 KERNEL_LOADADDR := 0x00008000
 
+SIGNATURE:=$(shell printf "%.8s" $(SOURCE_DATE_EPOCH))
+
 define Build/dtb
-        $(call Image/BuildDTB,$(DTS_DIR)/$(DEVICE_DTS).dts,$@.dtb)
+	$(call Image/BuildDTB,$(DTS_DIR)/$(DEVICE_DTS).dts,$@.dtb)
 endef
 
 # SD-Card Images:
@@ -43,6 +45,7 @@ endef
 
 define Build/sdcard-img
 	ROOTFS_SIZE=$$(( $(CONFIG_TARGET_ROOTFS_PARTSIZE) * 1024 * 2 )); \
+	SIGNATURE="$(SIGNATURE)" \
 	./gen_mvebu_sdcard_img.sh $@ \
 		"$(STAGING_DIR_IMAGE)/clearfog-u-boot-spl.kwb" \
 		c 32768 $@.boot \

target/linux/mvebu/image/gen_mvebu_sdcard_img.sh

 #!/usr/bin/env bash
 #
 # Copyright (C) 2016 Josua Mayer
-# 
+#
 # This program is free software; you can redistribute it and/or
 # modify it under the terms of the GNU General Public License
 # as published by the Free Software Foundation; either version 2
@@ -40,7 +40,7 @@ dd if=/dev/zero of="$OUTFILE" bs=512 count=1 >/dev/null
 printf "Done\n"
 
 while [ "$#" -ge 3 ]; do
-	ptgen_args="$ptgen_args -p $(($2 / 2 + 256)) -S 0x$1"
+	ptgen_args="$ptgen_args -t $1 -p $(($2 / 2 + 256))"
 	parts="$parts$3 "
 	shift; shift; shift
 done
@@ -50,7 +50,7 @@ sect=63
 
 # create real partition table using fdisk
 printf "Creating partition table: "
-set `ptgen -o "$OUTFILE" -h $head -s $sect -l 1024 $ptgen_args`
+set `ptgen -o "$OUTFILE" -h $head -s $sect -l 1024 -S 0x$SIGNATURE $ptgen_args`
 printf "Done\n"
 
 # install bootloader