staging: rtl8192u: remove redundant null check on array alg

u.crypt.alg is an array of u8 integers and hence the null check on
this array is redundant and can be removed.

Detected with CoverityScan, CID#143214 ("Array compared against 0")

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>