bnxt_en: Add warning message about disallowed speed change

Some chips may not allow changing default speed when dual rate
transceivers modules are used. Firmware on those chips will
indicate the same to the driver.

Add a warning message when speed change is not supported
because a dual rate transceiver is detected by the NIC.

Signed-off-by: Sreekanth Reddy <sreekanth.reddy@broadcom.com>
Reviewed-by: Kalesh AP <kalesh-anakkur.purayil@broadcom.com>
Reviewed-by: Somnath Kotur <somnath.kotur@broadcom.com>
Reviewed-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Link: https://lore.kernel.org/r/20240402093753.331120-8-pavan.chebbi@broadcom.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>