wifi: ath12k: fix skb_ext_desc leak in ath12k_dp_tx() error path

wifi: ath12k: fix skb_ext_desc leak in ath12k_dp_tx() error path

When vlan support was added, we missed that when
ath12k_dp_prepare_htt_metadata() returns an error we also need to free
the skb holding the metadata before going on with the cleanup process.

Compile tested only.

Fixes: 26dd8ccdba4d ("wifi: ath12k: dynamic VLAN support")
Signed-off-by: Nicolas Escande <nico.escande@gmail.com>
Reviewed-by: Aditya Kumar Singh <aditya.kumar.singh@oss.qualcomm.com>
Link: https://patch.msgid.link/20250122160112.3234558-1-nico.escande@gmail.com
Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>