drivers: kscan: generalize and improve FT5336 driver

The FT5336 driver has been improved and generalized so that multiple
Focaltech touch controllers can be supported using the same single
driver. According to specifications the following list of controller
variants should be supported: FT5x06, FT5606, FT5x16, FT6x06, Ft6x36,
FT5x06i, FT5336, FT3316, FT5436i, FT5336i and FT5x46.

Tested using ER-TFTM028-4 display module (FT6X06).

Signed-off-by: Gerard Marull-Paretas <gerard@teslabs.com>