Fix: watchdog timed out, if using sha1 command

* Fix: if using sha1 command watchdog timed out
* change function call sha1_csum(..) to the watchdog-safe variant
  sha1_csum_wd(..) to support watchdog reset

Signed-off-by: Jens Scharsig <esw@bus-elektronik.de>
diff --git a/common/cmd_sha1sum.c b/common/cmd_sha1sum.c
index bb3cff0..2b2dd8b 100644
--- a/common/cmd_sha1sum.c
+++ b/common/cmd_sha1sum.c
@@ -37,7 +37,7 @@
 	addr = simple_strtoul(argv[1], NULL, 16);
 	len = simple_strtoul(argv[2], NULL, 16);
 
-	sha1_csum((unsigned char *) addr, len, output);
+	sha1_csum_wd((unsigned char *) addr, len, output, CHUNKSZ_SHA1);
 	printf("SHA1 for %08lx ... %08lx ==> ", addr, addr + len - 1);
 	for (i = 0; i < 20; i++)
 		printf("%02x", output[i]);