RDMA/nes: Make nesadapter->phy_lock usage consistent

nes_{read,write}_1G_phy_reg() are using phy_lock while
nes_{read,write}_10G_phy_reg() leave that to the caller.

Remove phy_lock from 1G routines and leave the locking to the caller.
Add additional phy_lock calls around 1G read/write.

Signed-off-by: Chien Tung <chien.tin.tung@intel.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>