bnx2x: EEE code refactoring

In order to lay the foundation for 1G EEE support, several segments of code
which are common to both 1G and 10G EEE configurations were extracted from
the 10G EEE configuration flow to their own functions.
E.g., bnx2x_eee_initial_config, bnx2x_eee_advertise, bnx2x_eee_disable, etc.

The rest of the EEE functions were relocated and placed in a single,
continuous section of the file.

Signed-off-by: Yuval Mintz <yuvalmin@broadcom.com>
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>