wifi: iwlwifi: rename ctx-info-gen3 to ctx-info-v2

Context info was introduced in 22000, and was significantly changed in
ax210. The new version of context info was called 'gen3',
probably because in 22000, the gen2 transport was added.

But this name is just wrong:
- if 'gen' enumerates transports, there was not a gen3 transport, just a
  few modifications to gen1/2 transports needed for ax210.
- if 'gen' enumerates devices, then we can just use the device names.

Also, context info will soon become a lib, agnostic of the transport
generations.
Simply replace 'gen3' with 'v2'.

Reviewed-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://patch.msgid.link/20250511195137.a580bd8d4f74.Ie413a02233f1a5ad538e13071c09760b9d97be3b@changeid