treewide: rename BIAS_DISABLE to BIAS_DISABLED

When we're reading the current bias setting of a line, it is already
disabled so the flag should be named as such. While BIAS_DISABLE would
technically be fine when modifying the setting, let's rename it to
BIAS_DISABLED too for consistency.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>