drivers: gpio: cc13xx_cc26xx: Remove multi functions

- It seems that the mask variants of GPIO functions are not present in
  the latest sdk, so replace those with direct register access.
- This was already done in [0], but was reverted due to some hal
  problems.
- I am working on a hal update, but since this change does not require a
  hal update to work, it would be best to merge this first.

[0]: https://github.com/zephyrproject-rtos/zephyr/pull/83402

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