net: ena: Add debugfs support to the ENA driver

Adding the base directory of debugfs to the driver.
In order for the folder to be unique per driver instantiation,
the chosen name is the device name.

This commit contains the initialization and the
base folder.

The creation of the base folder may fail, but is considered
non-fatal.

Signed-off-by: David Arinzon <darinzon@amazon.com>
Link: https://patch.msgid.link/20250617110545.5659-8-darinzon@amazon.com


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