PCI: cadence: Lower severity of message when phy-names property is absent in DTS

The "phy-names" property is optional, so the message indicating its
absence during the probe should be of "info" severity rather than
"error" severity.

Link: https://lore.kernel.org/r/20241018113045.2050295-1-bwawrzyn@cisco.com


Signed-off-by: Bartosz Wawrzyniak <bwawrzyn@cisco.com>
[kwilczynski: update log messages wording, commit log]
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>