subsys: console: getchar: Use consistent var names for RX path

Initially, there was support only for buffered input, and adhoc var
names used. Later, buffered output support was added, with variables
consistently using "tx_" prefix. Now, rename the original RX path
to use symmetric "rx_" prefix.

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
1 file changed