input: synaptics_i2c_rmi4: Register for FB events

Register to recieve FB notifications and do suspend
when the display goes off and resume when it turns
back on.

CRs-fixed: 473492
Change-Id: I5ad02a7080225b724deae06d5443e0f9f8fd6929
Signed-off-by: Amy Maloche <amaloche@codeaurora.org>