drm/ili9486: Resolve clash in spi_device_id names

For "Really Good Reasons" [1] the SPI core requires a match
between compatible device strings and the name in spi_device_id.

The ili9486 driver uses compatible strings "waveshare,rpi-lcd-35"
and "ozzmaker,piscreen", but "rpi-lcd-35" and "piscreen" are missing,
so add them.

Compatible string "ilitek,ili9486" is already used by
staging/fbtft/fb_ili9486, therefore leaving it present in ili9486 as an
spi_device_id causes the incorrect module to be loaded, therefore remove
this id.

[1] https://elixir.bootlin.com/linux/latest/source/drivers/spi/spi.c#L487



Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>