gpio: Fix pin's status display for pin with GPIOF_UNUSED function

Even pin with GPIOF_UNUSED function can have a label.
The criteria to add or not a space character is linked to label not to
the used/unused status.

Signed-off-by: Patrice Chotard <patrice.chotard@foss.st.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>