auxdisplay: charlcd: fix x/y command parsing

The x/y command parsing has been broken since commit 129957069e
("staging: panel: Fixed checkpatch warning about simple_strtoul()").

Commit b34050fadb ("auxdisplay: charlcd: Fix and clean up handling of
x/y commands") fixed some problems by rewriting the parsing code,
but also broke things further by removing the check for a complete
command before attempting to parse it.  As a result, parsing is
terminated at the first x or y character.

This reinstates the check for a final semicolon.  Whereas the original
code use strchr(), this is wasteful seeing as the semicolon is always
at the end of the buffer.  Thus check this character directly instead.

Signed-off-by: Mans Rullgard <mans@mansr.com>
Signed-off-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>

drivers/auxdisplay/charlcd.c

@@ -538,6 +538,9 @@ static inline int handle_lcd_special_code(struct charlcd *lcd)
 	}
 	case 'x':	/* gotoxy : LxXXX[yYYY]; */
 	case 'y':	/* gotoxy : LyYYY[xXXX]; */
+		if (priv->esc_seq.buf[priv->esc_seq.len - 1] != ';')
+			break;
+
 		/* If the command is valid, move to the new address */
 		if (parse_xy(esc, &priv->addr.x, &priv->addr.y))
 			charlcd_gotoxy(lcd);