phy: marvell: a3700: Use same timeout for all register polling

The timeout is set to PLL_LOCK_TIMEOUT in every call to
comphy_poll_reg. Remove this parameter from the function.

Signed-off-by: Marek Behun <marek.behun@nic.cz>
Reviewed-by: Stefan Roese <sr@denx.de>
Signed-off-by: Stefan Roese <sr@denx.de>