fit_tools: adjust code a bit, if there's no 64-bit arithmetics in the…

… used shell

fit_tools/fit-add-avm-header.sh

@@ -181,7 +181,8 @@ add_avm_header()
 	fi
 	debug "Input file: %s%s%s\n" "$__yf_ansi_bright_green__" "$img" "$__yf_ansi_reset__"
 	debug "Looking for FDT magic value at offset 0x00 ..."
-	if ! [ "$(dd if="$img" bs=4 count=1 2>"$null" | b2d)" = "3490578157" ]; then
+	fdt_magic="$(dd if="$img" bs=4 count=1 2>"$null" | b2d)"
+	if { [ "$fdt_magic" -gt 0 ] && [ "$fdt_magic" -ne 3490578157 ]; } || { [ "$fdt_magic" -lt 0 ] && [ "$fdt_magic" -ne -804389139 ]; }; then
 		debug "$(result 1 " failed")"
 		printf -- "Invalid FDT magic at start of input file '%s'.\a\n" "$img" 1>&2
 		exit 1

fit_tools/fit-findfs.sh

@@ -287,7 +287,6 @@ find_rootfs_in_fit_image()
 
 	img="$1"
 	magic="$(dd if="$img" bs=4 count=1 2>"$null" | b2d)"
-	[ "$magic" -lt 0 ] && magic=$(( magic & 0xffffffff ))
 	if ! [ "$magic" = "218164734" ]; then
 		printf "Invalid magic value (0x%08x) found at offset 0x%02x.\a\n" "$magic" "0" 1>&2
 		exit 1

fit_tools/fit-remove-avm-header.sh

@@ -276,7 +276,7 @@ remove_avm_header()
 	size=64
 	if [ "$dbg" = "1" ] && command -v hexdump 2>"$null" 1>&2; then
 		debug "\nData at offset 0x%02x, size %u:\n\n%s" "$offset" "$size" "$__yf_ansi_yellow__"
-		get_data "$img" "$size" "$offset" | hexdump -C | sed -n -e "1,$(( size / 16 ))p" 1>&2
+		get_data "$img" "$size" "$offset" | hexdump -C | sed -n -e "1,$(( size / 16 ))p" 1>&2 2>"$null"
 		debug "%s\n" "$__yf_ansi_reset__"
 	fi
 	offset=$(( offset + size ))