am33xx: Enable UART{1,2,3,4,5} pin-mux

If configured to use UART{1,2,3,4,5} such as on the Beaglebone RS232
cape or on the am335x_evm daughterboard, enable the proper pin-muxing.

Signed-off-by: Andrew Bradford <andrew@bradfordembedded.com>
diff --git a/board/ti/am335x/board.h b/board/ti/am335x/board.h
index 7985ab2..48e112e 100644
--- a/board/ti/am335x/board.h
+++ b/board/ti/am335x/board.h
@@ -44,6 +44,11 @@
  * is required on the board.
  */
 void enable_uart0_pin_mux(void);
+void enable_uart1_pin_mux(void);
+void enable_uart2_pin_mux(void);
+void enable_uart3_pin_mux(void);
+void enable_uart4_pin_mux(void);
+void enable_uart5_pin_mux(void);
 void enable_i2c0_pin_mux(void);
 void enable_board_pin_mux(struct am335x_baseboard_id *header);
 #endif