enic: detect admin channel resources for SR-IOV

Check for the presence of admin channel BAR resources
(RES_TYPE_ADMIN_WQ, ADMIN_RQ, ADMIN_CQ, SRIOV_INTR) during resource
discovery. Set has_admin_channel when all four are available.

Use ARRAY_SIZE(enic->admin_cq) for the admin CQ count check since the
driver allocates two admin CQs (one for WQ completions, one for RQ
completions) and both must be backed by hardware resources.

Add admin WQ, RQ, CQ and INTR fields to struct enic for use by the
upcoming admin channel open/close paths.

Signed-off-by: Satish Kharat <satishkh@cisco.com>
Link: https://patch.msgid.link/20260401-enic-sriov-v2-prep-v4-6-d5834b2ef1b9@cisco.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>