be2net: ignore mac-addr set call for an already programmed mac-addr

An ndo_set_mac_addr() call may be issued for a mac-addr that is already
active on an interface. If so, silently ignore the request. Sending such
a request to the FW, causes a "mac collision" error. The error is harmless
but is avoidable noise in the kernel log.

Signed-off-by: Vasundhara Volam <vasundhara.volam@emulex.com>
Signed-off-by: Sathya Perla <sathya.perla@emulex.com>
Signed-off-by: David S. Miller <davem@davemloft.net>