tg3: Do not enable APE on bcm5700

With older versions of the NVRAM format, the driver may mistakenly
determine that APE is enabled.  Make sure this doesn't happen by
restricting the ENABLE_APE check to devices known to have more
recent NVRAM image formats.

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