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>
In preparation for introducing a warning.
Unquoted string defaults work through a quirk of Kconfig (undefined
symbols get their name as their string value), but look confusing. It's
done inconsistently now too.
Suggested by Kumar Gala.
Signed-off-by: Ulf Magnusson <Ulf.Magnusson@nordicsemi.no>