net: pcs: xpcs: there is only one PHY ID

commit a54a8b71

 upstream.

The xpcs driver has an apparently inadequate structure for the actual
hardware it drives.

These defines and the xpcs_probe() function would suggest that there is
one PHY ID per supported PHY interface type, and the driver simply
validates whether the mode it should operate in (the argument of
xpcs_probe) matches what the hardware is capable of:

	#define SYNOPSYS_XPCS_USXGMII_ID	0x7996ced0
	#define SYNOPSYS_XPCS_10GKR_ID		0x7996ced0
	#define SYNOPSYS_XPCS_XLGMII_ID		0x7996ced0
	#define SYNOPSYS_XPCS_SGMII_ID		0x7996ced0
	#define SYNOPSYS_XPCS_MASK		0xffffffff

but that is not the case, because upon closer inspection, all the above
4 PHY ID definitions are in fact equal.

So it is the same XPCS that is compatible with all 4 sets of PHY
interface types.

This change introduces an array of struct xpcs_compat which is populated
by the single struct xpcs_id instance. It also eliminates the bogus
defines for multiple Synopsys XPCS PHY IDs and replaces them with a
single XPCS_ID, which better reflects the way in which the hardware
operates.

Because we are touching this area of the code anyway, the new array of
struct xpcs_compat, as well as the array of xpcs_id, have been moved
towards the end of the file, since they are variable declarations not
definitions. If whichever of struct xpcs_compat or struct xpcs_id need
to gain a function pointer member in the future, it is easier to
reference functions (no forward declarations needed) if we have the
const variable declarations at the end of the file.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Yongxin Liu <yongxin.liu@windriver.com>