staging: rtl8188eu: remove unneeded conversions to bool

Patch suppresses the following warning issued by coccicheck:
WARNING: conversion to bool not needed here

Signed-off-by: Aishwarya Pant <aishpant@gmail.com>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>