net: atlantic: check rpc result and wait for rpc address

Artificial HW reliability tests revealed a possible hangup in
the driver. Normally, when device disappears from bus, all
register reads returns 0xFFFFFFFF.

At remote procedure invocation towards FW there is a logic
where result is compared with -1 in a loop.
That caused an infinite loop if hardware due to some issues
disappears from bus.

Add extra result checks to prevent this.

Signed-off-by: Dmitry Bogdanov <dbogdanov@marvell.com>
Signed-off-by: Igor Russkikh <irusskikh@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>