qed: fix double free in qed_cxt_tables_alloc()

In the Linux kernel, the following vulnerability has been resolved: qed: fix double free in qed_cxt_tables_alloc() If one of the later PF or VF CID bitmap allocations fails, qed_cid_map_alloc() jumps to cid_map_fail and frees the previously allocated CID bitmaps before returning an error. qed_cxt_tables_alloc() then calls qed_cxt_mngr_free(), which invokes qed_cid_map_free() again. Fix this by setting each CID bitmap pointer to NULL after bitmap_free() to avoid double free. The bug was first flagged by an experimental analysis tool we are developing for kernel memory-management bugs while analyzing v6.13-rc1. The tool is still under development and is not yet publicly available. Manual inspection confirms that the bug is still present in v7.1-rc3. Runtime reproduction was not attempted because exercising the failing allocation path requires device-specific setup.