bng_en: make bnge_alloc_ring() self-unwind on failure

bng_en: make bnge_alloc_ring() self-unwind on failure

Ensure bnge_alloc_ring() frees any intermediate allocations
when it fails. This enables later patches to rely on this
self-unwinding behavior.

Signed-off-by: Bhargava Marreddy <bhargava.marreddy@broadcom.com>
Reviewed-by: Vikas Gupta <vikas.gupta@broadcom.com>
Reviewed-by: Rajashekar Hudumula <rajashekar.hudumula@broadcom.com>
Link: https://patch.msgid.link/20250919174742.24969-2-bhargava.marreddy@broadcom.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>