mlx4ib: Fix EQ resource leak on mlx4_ib_add() error path

[ing.castellanosdz_gmail.com]

Summary

In mlx4_ib_add(), the normal teardown path calls mlx4_ib_free_eqs()
but the err_map error path jumps directly to iounmap() without freeing
EQs, leaking the resource.

Add mlx4_ib_free_eqs() call before iounmap in the error path, matching
the cleanup order of the normal teardown.

Patch by Haoxiang Li.
Bug: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=295637
Verified: patch applies cleanly on 14.5-RELEASE

Test Plan

Patch applies cleanly on FreeBSD 14.5-RELEASE (Hunk #1 at 2773). Code review confirmed leak by comparing error path (line 2747) vs normal teardown (line 2856).