drivers: pinmux stm32F1 remap IP without changing the SWJ_CFG

Change the REMAP bits of the AFIO_MAPR of the stm32F1x soc
with local MACRO without changing the SWJ_CFG (write-only bits).
The serial wire JTAG configuration is taken from the Z_AFIO_REMAP
(value of the CONFIG_GPIO_STM32_SWJ_xxx))
and not read from the MAPR register.
It accesses to the MAPR register directly instead of LL functions.
Note that Remapping on the MAPR2 is not to change.

Signed-off-by: Francois Ramu <francois.ramu@st.com>