x86/intel_rdt: Select KERNFS when enabling INTEL_RDT_A

arch/x86/kernel/cpu/intel_rdt_rdtgroup.c: In function 'rdtgroup_kn_lock_live':
arch/x86/kernel/cpu/intel_rdt_rdtgroup.c:658:2: error: implicit declaration of
function 'kernfs_break_active_protection' [-Werror=implicit-function-declaration]

Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Shaohua Li <shli@fb.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Tony Luck <tony.luck@intel.com>

arch/x86/Kconfig

@@ -411,6 +411,7 @@ config INTEL_RDT_A
 	bool "Intel Resource Director Technology Allocation support"
 	default n
 	depends on X86 && CPU_SUP_INTEL
+	select KERNFS
 	help
 	  Select to enable resource allocation which is a sub-feature of
 	  Intel Resource Director Technology(RDT). More information about