phy: cadence: salvo: Constify cdns_nxp_sequence_pair

cdns_nxp_sequence_pair[] are never modified and can be made const to allow
the compiler to put them in read-only memory.

Signed-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com>
Reviewed-by: Peter Chen <peter.chen@nxp.com>
Link: https://lore.kernel.org/r/20200912204639.501669-3-rikard.falkeborn@gmail.com


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