net: ena: fix coding style nits

This commit fixes two nits, but it does not generate any change to binary
because of the optimization of gcc.

  - use `count` instead of `channels->combined_count`
  - change return type from `int` to `bool`

Also add spaces and change macro order in OR assignment to make the code
easier to read.

Signed-off-by: Sameeh Jubran <sameehj@amazon.com>
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Signed-off-by: Shay Agroskin <shayagr@amazon.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>