net: macb: Perform zynqmp dynamic configuration only for SGMII interface

net: macb: Perform zynqmp dynamic configuration only for SGMII interface

In zynqmp platforms where firmware supports dynamic SGMII configuration
but has other non-SGMII ethernet devices, it fails them with no packets
received at the RX interface.

To fix this behaviour perform SGMII dynamic configuration only
for the SGMII phy interface.

Fixes: 32cee7818111 ("net: macb: Add zynqmp SGMII dynamic configuration support")
Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@amd.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Reported-by: Michal Simek <michal.simek@amd.com>
Tested-by: Michal Simek <michal.simek@amd.com>
Reviewed-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/1675340779-27499-1-git-send-email-radhey.shyam.pandey@amd.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>