STM32 uart Kconfig instance flags were not following
same naming scheme than other drivers (i2c, spi, ..)
Update driver to use UART_X instead of UART_STM32_PORT_X
Signed-off-by: Erwan Gouriou <erwan.gouriou@linaro.org>
Move all STM32 based board pinmux files into the board dirs so we are
consistent across all the STM32 platforms/boards.
Signed-off-by: Kumar Gala <kumar.gala@linaro.org>