[TG3]: Split tg3_phy_probe into 2 functions

Split the 1st half of tg3_phy_probe() into tg3_get_eeprom_hw_cfg() so
that the TG3_FLAG_EEPROM_WRITE_PROT can be determined before calling
tg3_set_power_state() in tg3_get_invariants(). This will allow
tg3_set_power_state() to drive the GPIOs correctly based on the config.
information in eeprom.

On the 5752, there are no pull-up resistors on the GPIO pins and it is
necessary to drive the unused GPIOs as output.

Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>