mx6slevk: Remove get_board_rev()

get_board_rev() just returns the cpu revision, which does not make it really
useful for distinguishing between revisions of the board.

Let's get rid of get_board_rev() as it is not being used with its correct
meaning.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>

board/freescale/mx6slevk/mx6slevk.c

@@ -308,11 +308,6 @@ int board_init(void)
 	return 0;
 }
 
-u32 get_board_rev(void)
-{
-	return get_cpu_rev();
-}
-
 int checkboard(void)
 {
 	puts("Board: MX6SLEVK\n");