net: ena: Capitalize all log strings and improve code readability

Capitalize all log strings printed by the ena driver to make their
format uniform across it.

Also fix indentation, spelling mistakes and comments to improve code
readability. This also includes adding comments to macros/enums whose
purpose might be difficult to understand.
Separate some code into functions to make it easier to understand the
purpose of these lines.

Signed-off-by: Amit Bernstein <amitbern@amazon.com>
Signed-off-by: Shay Agroskin <shayagr@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>