Staging: rtl8192u: Remove debug messages

As kmalloc generates a backtrace on failure so there is no need of
these debug messages when kmalloc fails. Also remove unwanted {} around if
block after removal of these messages.

Signed-off-by: Bhumika Goyal <bhumirks@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>