staging: hikey9xx: make phy_ops struct const

Fix the following type of checkpatch warning:
"WARNING: struct phy_ops should normally be const"

Signed-off-by: Atul Gopinathan <leoatul12@gmail.com>
Link: https://lore.kernel.org/r/20210209081935.3084-2-leoatul12@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>