boards: ti: beagleconnect_freedom: Remove PINCTRL

- PINCTRL is now being selected by
  soc/ti/simplelink/cc13x2x7_cc26x2x7/Kconfig, so no need to add to
  diffconfig.
- See https://github.com/zephyrproject-rtos/zephyr/pull/64718#discussion_r1734288793



Signed-off-by: Ayush Singh <ayush@beagleboard.org>