x86/ACPI: CPPC: Add missing include

Some minimial kernel configurations will fail with -Werror=implicit-function-declaration
due to a missing header include.

Add that header.

Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Link: https://patch.msgid.link/20250211203314.762755-1-superm1@kernel.org
[ rjw: Subject edit ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Author: superm1

arch/x86/kernel/acpi/cppc.c

@@ -4,6 +4,8 @@
  * Copyright (c) 2016, Intel Corporation.
  */
 
+#include <linux/bitfield.h>
+
 #include <acpi/cppc_acpi.h>
 #include <asm/msr.h>
 #include <asm/processor.h>