net: ethtool: Enhance error messages sent to user space

During the firmware flashing process, notifications are sent to user
space to provide progress updates. When an error occurs, an error
message is sent to indicate what went wrong.

In some cases, appropriate error messages are missing.

Add relevant error messages where applicable, allowing user space to better
understand the issues encountered.

Signed-off-by: Danielle Ratson <danieller@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20240910091044.3044568-1-danieller@nvidia.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>