global: Convert simple_strtoul() with hex to hextoul()

It is a pain to have to specify the value 16 in each call. Add a new
hextoul() function and update the code to use it.

Add a proper comment to simple_strtoul() while we are here.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/board/freescale/common/cmd_esbc_validate.c b/board/freescale/common/cmd_esbc_validate.c
index 638aa3c..6c09626 100644
--- a/board/freescale/common/cmd_esbc_validate.c
+++ b/board/freescale/common/cmd_esbc_validate.c
@@ -40,7 +40,7 @@
 		hash_str = argv[2];
 
 	/* First argument - header address -32/64bit */
-	haddr = (uintptr_t)simple_strtoul(argv[1], NULL, 16);
+	haddr = (uintptr_t)hextoul(argv[1], NULL);
 
 	/* With esbc_validate command, Image address must be
 	 * part of header. So, the function is called
diff --git a/board/freescale/common/fsl_validate.c b/board/freescale/common/fsl_validate.c
index 564a8b3..066aa9a 100644
--- a/board/freescale/common/fsl_validate.c
+++ b/board/freescale/common/fsl_validate.c
@@ -767,7 +767,7 @@
 	if (!p) {
 		return 0;
 	} else {
-		tmp = simple_strtoul(p, &endptr, 16);
+		tmp = hextoul(p, &endptr);
 		if (sizeof(ulong) == 4)
 			*num = cpu_to_be32(tmp);
 		else
diff --git a/board/freescale/common/sys_eeprom.c b/board/freescale/common/sys_eeprom.c
index be0fda0..9e73056 100644
--- a/board/freescale/common/sys_eeprom.c
+++ b/board/freescale/common/sys_eeprom.c
@@ -378,7 +378,7 @@
 	}
 
 	for (i = 0; *p && (i < 6); i++) {
-		e.mac[index][i] = simple_strtoul(p, &p, 16);
+		e.mac[index][i] = hextoul(p, &p);
 		if (*p == ':')
 			p++;
 	}
@@ -452,7 +452,7 @@
 		set_date(argv[2]);
 		break;
 	case 'p':	/* MAC table size */
-		e.mac_count = simple_strtoul(argv[2], NULL, 16);
+		e.mac_count = hextoul(argv[2], NULL);
 		update_crc();
 		break;
 	case '0' ... '9':	/* "mac 0" through "mac 22" */