phy: ralink-usb: Constify ralink_usb_phy_ops

The only usage is to pass its address to devm_phy_create() which takes a
const pointer. Make it const to allow the compiler to put it in
read-only memory.

Signed-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com>
Link: https://lore.kernel.org/r/20200823220025.17588-7-rikard.falkeborn@gmail.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>