net: qcom/emac: Reduce timeout for mdio read/write

Currently mdio read/write takes around ~115us as the timeout
between status check is set to 100us.
By reducing the timeout to 1us mdio read/write takes ~15us to
complete. This improves the link up event response.

Signed-off-by: Hemanth Puranik <hpuranik@codeaurora.org>
Acked-by: Timur Tabi <timur@codeaurora.org>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>