scsi: cxgb4i: fix Tx skb leak

[ Upstream commit 9b3a081fb62158b50bcc90522ca2423017544367 ]

In case of connection reset Tx skb queue can have some skbs which are
not transmitted so purge Tx skb queue in release_offload_resources() to
avoid skb leak.

Signed-off-by: Varun Prakash <varun@chelsio.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>