When the PHY is first coming up (or resuming from suspend), it's
possible that although the FW status shows as running, we still see
zeroes in the GLOBAL_CFG set of registers and cannot determine available
modes. Since all models support 10M, add a poll and wait the config to
become available.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>