HID: i2c-hid: fix ret_count check

ret_count has to be at least 3, as we have to count the 2 bytes that are used
for the size of the reply. Without this, memcpy() might be called with zero or
negative count.

Reported-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/drivers/hid/i2c-hid/i2c-hid.c b/drivers/hid/i2c-hid/i2c-hid.c
index ce01d59..6e1774c 100644
--- a/drivers/hid/i2c-hid/i2c-hid.c
+++ b/drivers/hid/i2c-hid/i2c-hid.c
@@ -520,7 +520,7 @@
 
 	ret_count = ihid->inbuf[0] | (ihid->inbuf[1] << 8);
 
-	if (!ret_count)
+	if (ret_count <= 2)
 		return 0;
 
 	ret_count = min(ret_count, ask_count);