pinctrl: generic: rename PIN_CONFIG_OUTPUT to LEVEL

pinctrl: generic: rename PIN_CONFIG_OUTPUT to LEVEL

This generic pin config property is confusingly named so let's
rename it to make things clearer.

There are already drivers in the tree that use PIN_CONFIG_OUTPUT
to *read* the value of an output driven pin, which is a big
semantic confusion for the head: are we then reading the
setting of the output or the actual value/level that is put
out on the pin?

We already have PIN_CONFIG_OUTPUT_ENABLE that turns on driver
buffers for output, so this can by logical conclusion only
drive the voltage level if it should be any different.

But if we read the pin, are we then reading the *setting* of
the output value or the *actual* value we can see on the
line?

If the pin has not first been set into output mode with
PIN_CONFIG_OUTPUT_ENABLE, but is instead in some input mode
or tristate, what will reading this property actually
return?

Reading the current users reading this property it is clear
that what we read is the logical level of the pin as 0 or 1
depending on if it is low or high.

Rename it to PIN_CONFIG_LEVEL so it is crystal clear that
we set or read the voltage level of the pin and nothing else.

Acked-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>