MLK-17837-01 input: misc: rpmsg_input: add rpmsg virtual sensor driver

MLK-17837-01 input: misc: rpmsg_input: add rpmsg virtual sensor driver

NXP i.MX7ULP EVK boards all sensors connect with M4 core, A core
has to conmunicate with sensors by virtual io bus like rpmsg bus.
The driver implement the virtual sensor input driver to configure
sensors active/idle/delay actions and report the sensors' event to
user space.

Supply below sysfs for user to enable/disable detector and counter,
set poll delay:
	/sys/class/misc/step_counter/enable
	/sys/class/misc/step_detector/enable
	/sys/class/misc/step_counter/poll_delay

Reviewed-by: Elven Wang <elven.wang@nxp.com>
Signed-off-by: Fugang Duan <fugang.duan@nxp.com>