r8152: split DRIVER_VERSION

Split DRIVER_VERSION into NETNEXT_VERSION and NET_VERSION. Then,
according to the value of DRIVER_VERSION, we could know which
patches are used generally without comparing the source code.

Signed-off-by: Hayes Wang <hayeswang@realtek.com>
Signed-off-by: David S. Miller <davem@davemloft.net>