HID: do not call hid_set_drvdata(hdev, NULL) in drivers

This is a common pattern in the HID drivers to reset the drvdata. Some
do it properly, some do it only in case of failure.

But, this is actually already handled by driver core, so there is no need
to do it manually.

[for hid-sensor-hub.c]
Acked-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
[For hid-picolcd_core.c]
Acked-by: Bruno Prémont <bonbons@linux-vserver.org>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>