ipw2x00: Fix potential NULL dereference in libipw_xmit()

[ Upstream commit e8366bbabe1d207cf7c5b11ae50e223ae6fc278b ]

crypt and crypt->ops could be null, so we need to checking null
before dereference

Signed-off-by: Haowen Bai <baihaowen@meizu.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/1648797055-25730-1-git-send-email-baihaowen@meizu.com


Signed-off-by: Sasha Levin <sashal@kernel.org>