wl3501_cs: Remove unnecessary NULL check

wl3501_cs: Remove unnecessary NULL check

[ Upstream commit 1d2a85382282e7c77cbde5650335c3ffc6073fa1 ]

In wl3501_detach(), link->priv is checked for a NULL value before being
passed to free_netdev(). However, it cannot be NULL at this point as it
has already been passed to other functions, so just remove the check.

Addresses-Coverity: CID 710499: Null pointer dereferences (REVERSE_INULL)
Signed-off-by: Alex Dewar <alex.dewar90@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200926174558.9436-1-alex.dewar90@gmail.com
Stable-dep-of: 391af06a02e7 ("wifi: wl3501_cs: Fix an error handling path in wl3501_probe()")
Signed-off-by: Sasha Levin <sashal@kernel.org>