net: qrtr: revert check in qrtr_endpoint_post()

I tried to make this check stricter as a hardenning measure but it broke
audo and wifi on these devices so revert it.

Fixes: aaa8e492 ("net: qrtr: make checks in qrtr_endpoint_post() stricter")
Reported-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Tested-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>