qed: fix double free in qed_cxt_tables_alloc()

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.

Fixes: fe56b9e6a8d9 ("qed: Add module with basic common support")
Cc: stable@vger.kernel.org
Signed-off-by: Zilin Guan <zilin@seu.edu.cn>
Signed-off-by: Dawei Feng <dawei.feng@seu.edu.cn>
Link: https://patch.msgid.link/20260520070323.2762379-1-dawei.feng@seu.edu.cn
Signed-off-by: Jakub Kicinski <kuba@kernel.org>