UBUNTU: SAUCE: net: ena: fix issues in setting interrupt moderation params in ethtool

UBUNTU: SAUCE: net: ena: fix issues in setting interrupt moderation params in ethtool

BugLink: https://bugs.launchpad.net/bugs/1853180
Issue 1:
--------
Reproduction steps:
1. sudo ethtool -C eth0 rx-usecs 128
2. sudo ethtool -C eth0 adaptive-rx on
3. sudo ethtool -C eth0 adaptive-rx off
4. ethtool -c eth0

expected output: rx-usecs 128
actual output: rx-usecs 0

Reason for issue:
In stage 3, ethtool userspace calls first the ena_get_coalesce() handler
to get the current value of all properties, and then the ena_set_coalesce()
handler. When ena_get_coalesce() is called the adaptive interrupt
moderation is still on. There is an if in the code that returns the
rx_coalesce_usecs only if the adaptive interrupt moderation is off.
And since it is still on, rx_coalesce_usecs is not set, meaning it
stays 0.

Solution to issue:
Remove this if static interrupt moderation intervals have nothing to do with
dynamic ones.

Issue 2:
--------
Reproduction steps:
1. sudo ethtool -C eth0 rx-usecs 128
2. sudo ethtool -C eth0 adaptive-rx on
3. sudo ethtool -C eth0 rx-usecs 128
4. ethtool -c eth0

expected output: rx-usecs 128
actual output: rx-usecs 0

Reason for issue:
In stage 3, when ena_set_coalesce() is called, the handler tests if
rx adaptive interrupt moderation is on, and if it is, it returns before
getting to the part in the function that sets the rx non-adaptive
interrupt moderation interval.

Solution to issue:
Remove the return from the function when rx adaptive interrupt moderation
is on.

Additional small fixes in this commit:
--------------------------------------
1. Remove 2 unnecessary comments.
2. Remove 4 unnecesary "{}" in single row if statements.
3. Reorder ena_set_coalesce() to make sense.
4. Change the names of ena_update_tx/rx_rings_intr_moderation()
   functions to ena_update_tx/rx_rings_nonadaptive_intr_moderation() for
   clarity.

Signed-off-by: Arthur Kiyanovski <akiyano@amazon.com>
Reference: https://lore.kernel.org/netdev/1572868728-5211-1-git-send-email-akiyano@amazon.com/
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Acked-by: Khaled Elmously <khalid.elmously@canonical.com>
Acked-by: Connor Kuehl <connor.kuehl@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>