cxl: Simplify bool conversion

Fix the following coccicheck warning:
./drivers/misc/cxl/sysfs.c:181:48-53: WARNING: conversion to bool not
needed here

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Reviewed-by: Andrew Donnellan <ajd@linux.ibm.com>
Acked-by: Frederic Barrat <fbarrat@linux.ibm.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Link: https://lore.kernel.org/r/1611908705-98507-1-git-send-email-yang.lee@linux.alibaba.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>