RDMA/irdma: Refactor GEN2 auxiliary driver

RDMA/irdma: Refactor GEN2 auxiliary driver

Refactor the irdma auxiliary driver and associated interfaces out of main.c
and into a standalone GEN2-specific source file and rename as gen_2 driver.

This is in preparation for adding GEN3 auxiliary drivers. Each HW
generation will have its own gen-specific interface file.

Additionally, move the Address Handle hash table and associated locks
under rf struct. This will allow GEN3 code to migrate to use it easily.

Signed-off-by: Mustafa Ismail <mustafa.ismail@intel.com>
Co-developed-by: Tatyana Nikolova <tatyana.e.nikolova@intel.com>
Signed-off-by: Tatyana Nikolova <tatyana.e.nikolova@intel.com>
Link: https://patch.msgid.link/20250827152545.2056-2-tatyana.e.nikolova@intel.com
Tested-by: Jacob Moroni <jmoroni@google.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>