common: Fix autocompletion with CONFIG_CMDLINE_PS_SUPPORT

The autocompletion did not work if CONFIG_CMDLINE_PS_SUPPORT was enabled
because U-Boot was comparing the prompt string with CONFIG_SYS_PROMPT .
While this works if CONFIG_CMDLINE_PS_SUPPORT is disabled, this no longer
works if it's enabled because user can override the PS1 . Fix this by
checking prompt string against the current PS1 value.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Tom Rini <trini@konsulko.com>
diff --git a/common/command.c b/common/command.c
index e192bb2..db25bf5 100644
--- a/common/command.c
+++ b/common/command.c
@@ -356,8 +356,13 @@
 	int i, j, k, len, seplen, argc;
 	int cnt;
 	char last_char;
+#ifdef CONFIG_CMDLINE_PS_SUPPORT
+	const char *ps_prompt = env_get("PS1");
+#else
+	const char *ps_prompt = CONFIG_SYS_PROMPT;
+#endif
 
-	if (strcmp(prompt, CONFIG_SYS_PROMPT) != 0)
+	if (strcmp(prompt, ps_prompt) != 0)
 		return 0;	/* not in normal console */
 
 	cnt = strlen(buf);