Check GPIOF_ALTERABLE_EDGE before trying to open edge file in ugpio_full_open

Patch by Fredrik Svensson.

Signed-off-by: Michael Heimpold <mhei@heimpold.de>
Fix return value in ugpio_direction_input

Patch by Fredrik Svensson.

Signed-off-by: Michael Heimpold <mhei@heimpold.de>
Fix a "comment inside comment" warning

Patch by Fredrik Svensson.

Signed-off-by: Michael Heimpold <mhei@heimpold.de>