Input: bcm5974 - Convert to MT-B

Use of the in-kernel tracking code to convert the driver to MT-B.

With ten fingers on the pad, the in-kernel tracking adds approximately
25 us to the maximum irqsoff latency. Under normal workloads, however,
the tracking has no measurable effect.

Tested-by: Benjamin Tissoires <benjamin.tissoires@enac.fr>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Henrik Rydberg <rydberg@euromail.se>