tg3: Fix APE mutex init and use

APE mutex register blocks are shared by all ports of multiport devices.
For some mutexing purposes, each function is assigned their own
register.  For other cases, each function is assigned its own request
and grant bits of a single register.  For the latter cases, the tg3
driver is incorrectly allowing each function to use the same set of
grant / request bits.  This patch fixes the code so that each function
uses the appropriate bitset.

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>