common: cli_hush: avoid dead code

Condition "(value == NULL && ++value == NULL)" actully will
always return false.

Instead, use condition "(value == NULL || *(value + 1) == 0)" to detect
such expression "c=". To "c=", *(value + 1) is 0, so directly return -1,
but not continue.
Signed-off-by: NPeng Fan <Peng.Fan@freescale.com>
Cc: Rabin Vincent <rabin@rab.in>
Cc: Simon Glass <sjg@chromium.org>
Cc: Tom Rini <trini@konsulko.com>
Reviewed-by: NSimon Glass <sjg@chromium.org>

common/cli_hush.c

@@ -2162,7 +2162,7 @@ int set_local_var(const char *s, int flg_export)
 	 * NAME=VALUE format.  So the first order of business is to
 	 * split 's' on the '=' into 'name' and 'value' */
 	value = strchr(name, '=');
-	if (value == NULL && ++value == NULL) {
+	if (value == NULL || *(value + 1) == 0) {
 		free(name);
 		return -1;
 	}