Input: synaptics-rmi4 - allow to add attention data

The HID implementation of RMI4 provides the data during
the interrupt (in the input report). We need to provide
a way for this transport driver to provide the attention
data while calling an IRQ.

We use a fifo in rmi_core to not lose any incoming event.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Reviewed-by: Andrew Duggan <aduggan@synaptics.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>