HID: hid-sensor-custom: simplify getting .driver_data

We should get 'driver_data' from 'struct device' directly. Going via
platform_device is an unneeded step back and forth.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>