net/mlx5: Check firmware sync reset requested is set before trying to abort it

In case driver sent NACK to firmware on sync reset request, it will get
sync reset abort event while it didn't set sync reset requested mode.
Thus, on abort sync reset event handler, driver should check reset
requested is set before trying to stop sync reset poll.

Fixes: 7dd6df32

 ("net/mlx5: Handle sync reset abort event")
Signed-off-by: Moshe Shemesh <moshe@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>