net/mlx4_en: Remove the redundant NULL check for the 'my_ets' object

net/mlx4_en: Remove the redundant NULL check for the 'my_ets' object

Static analysis shows that pointer "my_ets" cannot be NULL because it
points to the object "struct ieee_ets".

Remove the extra NULL check. It is meaningless and harms the readability
of the code.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Signed-off-by: Andrey Vatoropin <a.vatoropin@crpt.ru>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20250616045034.26000-1-a.vatoropin@crpt.ru
Signed-off-by: Paolo Abeni <pabeni@redhat.com>