atm: nicstar: Unmap DMA on send error

atm: nicstar: Unmap DMA on send error

[ Upstream commit 6dceaa9f56e22d0f9b4c4ad2ed9e04e315ce7fe5 ]

The `skb' is mapped for DMA in ns_send() but does not unmap DMA in case
push_scqe() fails to submit the `skb'. The memory of the `skb' is
released so only the DMA mapping is leaking.

Unmap the DMA mapping in case push_scqe() failed.

Fixes: 864a3ff635fa7 ("atm: [nicstar] remove virt_to_bus() and support 64-bit platforms")
Cc: Chas Williams <3chas3@gmail.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>