drivers: pinmux: stm32: fix MAPR remap

- Move SWJ_CFG initialization into pinmux.
- Don't disable the AFIO clock after SWJ_CFG
  initialization.
- Apply '111' to the SWJ_CFG bits upon remap
  application, that fixes the remap usage.

Signed-off-by: Georgij Cernysiov <geo.cgv@gmail.com>