Input: synaptics-rmi4 - remove unneeded struct register_offset

Input: synaptics-rmi4 - remove unneeded struct register_offset

All register offsets are fixed, and a number of places even read or
write multiple registers as a block, so there is no way to support
reordering them without move involved changes. Remove the unneeded level
of indirection in the register access.

Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Link: https://lore.kernel.org/r/20220608124808.51402-8-matthias.schiffer@ew.tq-group.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>