HID: fix a crash in hid_report_raw_event() function.

I'm using a Data Modul EasyTouch USB multitouch controller,
which is issuing a hid report with a size equals to 0. The rsize
value gets set to 536870912 and Linux is crashing in the memset
because the value is too big.

Signed-off-by: Armando Visconti <armando.visconti@st.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>