ixgbe: downgrade logging of unsupported VF API version to debug

ixgbe: downgrade logging of unsupported VF API version to debug

The ixgbe PF driver logs an info message when a VF attempts to negotiate an
API version which it does not support:

  VF 0 requested invalid api version 6

The ixgbevf driver attempts to load with mailbox API v1.5, which is
required for best compatibility with other hosts such as the ESX VMWare PF.

The Linux PF only supports API v1.4, and does not currently have support
for the v1.5 API.

The logged message can confuse users, as the v1.5 API is valid, but just
happens to not currently be supported by the Linux PF.

Downgrade the info message to a debug message, and fix the language to
use 'unsupported' instead of 'invalid' to improve message clarity.

Long term, we should investigate whether the improvements in the v1.5 API
make sense for the Linux PF, and if so implement them properly. This may
require yet another API version to resolve issues with negotiating IPSEC
offload support.

Fixes: 339f28964147 ("ixgbevf: Add support for new mailbox communication between PF and VF")
Reported-by: Yifei Liu <yifei.l.liu@oracle.com>
Link: https://lore.kernel.org/intel-wired-lan/20240301235837.3741422-1-yifei.l.liu@oracle.com/
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Tested-by: Rafal Romanowski <rafal.romanowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>