net/smsc911x: Fix ready check in cases where WORD_SWAP is needed

The chip ready check added by the commit 3ac3546e [Always wait for
the chip to be ready] does not work when the register read/write
is word swapped. This check has been added before the WORD_SWAP
register is programmed, so we need to check for swapped register
value as well.

Bit 16 is marked as RESERVED in SMSC datasheet, Steve Glendinning
<steve@shawell.net> checked with SMSC and wrote:

  The chip architects have concluded we should be reading PMT_CTRL
  until we see any of bits 0, 8, 16 or 24 set.  Then we should read
  BYTE_TEST to check the byte order is correct (as we already do).

  The rationale behind this is that some of the chip variants have
  word order swapping features too, so the READY bit could actually
  be in any of the 4 possible locations.  The architects have confirmed
  that if any of these 4 positions is set the chip is ready.  The other
  3 locations will either never be set or can only go high after READY
  does (so also indicate the device is ready).

This change will check for the READY bit at the 16th position. We do
not check the other two cases (bit 8 and 24) since the driver does not
support byte-swapped register read/write.

Signed-off-by: Kamlakant Patel <kamlakant.patel@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>