net/ncsi: Probe single packages to avoid conflict

Currently the NCSI driver sends a select-package command to all possible
packages simultaneously to discover what packages are available. However
at this stage in the probe process the driver does not know if
hardware arbitration is available: if it isn't then this process could
cause collisions on the RMII bus when packages try to respond.

Update the probe loop to probe each package one by one, and once
complete check if HWA is universally supported.

Signed-off-by: Samuel Mendoza-Jonas <sam@mendozajonas.com>
Signed-off-by: David S. Miller <davem@davemloft.net>