staging: rtl8192e: Fix incorrect pointer check

staging: rtl8192e: Fix incorrect pointer check

In commit 92172da23c56 ("staging: rtl8192e: replace comparison to NULL
by bool") a check was changed from looking at the data to the pointer,
which was incorrect, so revert that portion of the commit to have the
proper logic restored.

Reported-by: Julia Lawall <julia.lawall@inria.fr>
Signed-off-by: Mitali Borkar <mitaliborkar810@gmail.com>
Fixes: 92172da23c56 ("staging: rtl8192e: replace comparison to NULL by bool")
Link: https://lore.kernel.org/r/YHG8qARLUX2KPWwI@kali
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>