staging: rtl8188eu: unneeded NULL check

before these NULL checks we are already checking it for NULL, and if
it is NULL then we are jumping to the error label and handling
the error before returning.
So we can reach this part of the code only if the variable is known
to be not NULL, and if we already know that it is not NULL, then no
need to check it again.

Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>