drivers: pinmux: esp32: Fix using gpio as IO at the same time.

Since PINMUX_INPUT_ENABLED == 1 and PINMUX_OUTPUT_ENABLED == 0,
we can not set a gpio port as input and output at the same time,

So we always set the gpio as input. Thus, the gpio can be used on
I2C drivers for example.

Signed-off-by: Vitor Massaru Iha <vitor@massaru.org>