enc28j60: fix RX buffer overflow

The enc28j60 driver doesn't check whether the length of the packet as reported
by the hardware fits into the preallocated buffer. When stressed, the hardware
may report insanely large packets even tough the "Receive OK" bit is set. Fix
this.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --cc drivers/net/enc28j60.c
Simple merge