HID: hidraw: add proper error handling to raw event reporting

If kmemdup() in hidraw_report_event() fails, we are not propagating
this fact properly.

Let hidraw_report_event() and hid_report_raw_event() return an error
value to the caller.

Reported-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>