fbtft: make it possible to override regwidth

Honour regwidth in platform data.
8-bit controllers interfaced with a 16-bit SPI interface circuit,
need to change the register width.
fb_ili948{1,6}: regwidth was incorrect

Regwidth was incorrectly set to 16. It should be 8.
This was probably because they where used with a 16-bit
SPI interface circuit. Change fbtft_device entries on
the relevant entries.

Signed-off-by: Jon Cross
Acked-by: Noralf Tronnes <notro@tronnes.org>
fbtft_device: add Tontec 3.5 support

Signed-off-by: Jon Cross
Acked-by: Noralf Tronnes <notro@tronnes.org>