cmd_date: constify

Many strings in this file need not be writable.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/common/cmd_date.c b/common/cmd_date.c
index 8dbf16d..f0fa02a 100644
--- a/common/cmd_date.c
+++ b/common/cmd_date.c
@@ -31,7 +31,7 @@
 
 DECLARE_GLOBAL_DATA_PTR;
 
-const char *weekdays[] = {
+static const char * const weekdays[] = {
 	"Sun", "Mon", "Tues", "Wednes", "Thurs", "Fri", "Satur",
 };
 
@@ -41,7 +41,7 @@
 #define RELOC(a)	a
 #endif
 
-int mk_date (char *, struct rtc_time *);
+int mk_date (const char *, struct rtc_time *);
 
 int do_date (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
@@ -106,7 +106,7 @@
 /*
  * simple conversion of two-digit string with error checking
  */
-static int cnvrt2 (char *str, int *valp)
+static int cnvrt2 (const char *str, int *valp)
 {
 	int val;
 
@@ -131,7 +131,7 @@
  * Some basic checking for valid values is done, but this will not catch
  * all possible error conditions.
  */
-int mk_date (char *datestr, struct rtc_time *tmp)
+int mk_date (const char *datestr, struct rtc_time *tmp)
 {
 	int len, val;
 	char *ptr;