net: ena: cosmetic: remove unnecessary code

1. Remove unused definition of DRV_MODULE_VERSION
2. Remove {} from single line-of-code ifs
3. Remove unnecessary comments from ena_get/set_coalesce()
4. Remove unnecessary extra spaces and newlines

Signed-off-by: Arthur Kiyanovski <akiyano@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>