Add the transport driver for devices using RMI4 over SPI.
Signed-off-by: NAndrew Duggan <aduggan@synaptics.com>
Tested-by: NBenjamin Tissoires <benjamin.tissoires@redhat.com>
Tested-by: NLinus Walleij <linus.walleij@linaro.org>
Tested-by: NBjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>