staging: fbtft: Update TODO

Now, after a few fixes we may consider the conversion to
the GPIO descriptor API is done.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20210503172114.27891-6-andriy.shevchenko@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/fbtft/TODO

-* convert all uses of the old GPIO API from <linux/gpio.h> to the
-  GPIO descriptor API in <linux/gpio/consumer.h> and look up GPIO
-  lines from device tree, ACPI or board files, board files should
-  use <linux/gpio/machine.h>
-
 * convert all these over to drm_simple_display_pipe and submit for inclusion
   into the DRM subsystem under drivers/gpu/drm - fbdev doesn't take any new
   drivers anymore.