HID: alps: Fix memory leak

A kfree(readbuf) call was missed if hid_hw_raw_request() fails, fix it.
Also avoid mixing direct return with goto in the error paths.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>