global: Convert simple_strtoul() with decimal to dectoul()

It is a pain to have to specify the value 10 in each call. Add a new
dectoul() function and update the code to use it.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/net/tftp.c b/net/tftp.c
index 00ab7ca..5baf528 100644
--- a/net/tftp.c
+++ b/net/tftp.c
@@ -554,8 +554,7 @@
 		for (i = 0; i+8 < len; i++) {
 			if (strcasecmp((char *)pkt + i, "blksize") == 0) {
 				tftp_block_size = (unsigned short)
-					simple_strtoul((char *)pkt + i + 8,
-						       NULL, 10);
+					dectoul((char *)pkt + i + 8, NULL);
 				debug("Blocksize oack: %s, %d\n",
 				      (char *)pkt + i + 8, tftp_block_size);
 				if (tftp_block_size > tftp_block_size_option) {
@@ -566,8 +565,7 @@
 			}
 			if (strcasecmp((char *)pkt + i, "timeout") == 0) {
 				timeout_val_rcvd = (unsigned short)
-					simple_strtoul((char *)pkt + i + 8,
-						       NULL, 10);
+					dectoul((char *)pkt + i + 8, NULL);
 				debug("Timeout oack: %s, %d\n",
 				      (char *)pkt + i + 8, timeout_val_rcvd);
 				if (timeout_val_rcvd != (timeout_ms / 1000)) {
@@ -578,16 +576,15 @@
 			}
 #ifdef CONFIG_TFTP_TSIZE
 			if (strcasecmp((char *)pkt + i, "tsize") == 0) {
-				tftp_tsize = simple_strtoul((char *)pkt + i + 6,
-							   NULL, 10);
+				tftp_tsize = dectoul((char *)pkt + i + 6,
+						     NULL);
 				debug("size = %s, %d\n",
 				      (char *)pkt + i + 6, tftp_tsize);
 			}
 #endif
 			if (strcasecmp((char *)pkt + i,  "windowsize") == 0) {
 				tftp_windowsize =
-					simple_strtoul((char *)pkt + i + 11,
-						       NULL, 10);
+					dectoul((char *)pkt + i + 11, NULL);
 				debug("windowsize = %s, %d\n",
 				      (char *)pkt + i + 11, tftp_windowsize);
 			}