staging: fbtft: ili9341: use macro FBTFT_REGISTER_SPI_DRIVER

staging: fbtft: ili9341: use macro FBTFT_REGISTER_SPI_DRIVER

[ Upstream commit 4912649e1cf0317bf563f91655e04a303cacaf8d ]

Using FBTFT_REGISTER_DRIVER resolves to a NULL struct spi_device_id. This
ultimately causes a warning when the module probes. Fixes it.

Signed-off-by: Raphael Gallais-Pou <rgallaispou@gmail.com>
Link: https://lore.kernel.org/r/20230718172024.67488-1-rgallaispou@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>