ks8842: Fix ks8842_tx_frame() for 16bit case.

As reported by Andrew:

drivers/net/ks8842.c: In function 'ks8842_handle_rx':
drivers/net/ks8842.c:428: warning: 'status' may be used uninitialized in this function

Just use the 32-bit status for all reads, and delete the useless
cast to 'int' when reading a u16 into 'len'.

Reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>