cfb_console: Fix function console_back

* Do not disable and enable the cursor again.

console_back() is called only from video_putc() which already turns
the cursor off at the beginning and turns it on at the end, so there
is no need to change the cursor in console_back().

Signed-off-by: Pali Rohár <pali.rohar@gmail.com>
Signed-off-by: Anatolij Gustschin <agust@denx.de>

drivers/video/cfb_console.c

@@ -721,7 +721,6 @@ static void console_scrollup(void)
 
 static void console_back(void)
 {
-	CURSOR_OFF;
 	console_col--;
 
 	if (console_col < 0) {
@@ -730,7 +729,6 @@ static void console_back(void)
 		if (console_row < 0)
 			console_row = 0;
 	}
-	CURSOR_SET;
 }
 
 static void console_newline(void)