x86/resctrl: Remove unused variable

Variable "struct rdt_resource *r" is set but not used. So remove it.

Signed-off-by: Peng Hao <peng.hao2@zte.com.cn>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/1552152584-26087-1-git-send-email-peng.hao2@zte.com.cn