fbcon: Use 'bool' where appopriate

Use 'bool' type where it makes more sense than 'int'.

v2: Rebase due to corrected 'fbcon_cursor_blink' initial value

Acked-by: Helge Deller <deller@gmx.de>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Helge Deller <deller@gmx.de>