x86/boot: Make the x86_init noop functions static

Make the noop functions in x86_init.c static in case they are used
locally only.

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180221094232.23462-1-jgross@suse.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/kernel/x86_init.c

@@ -26,11 +26,11 @@
 
 void x86_init_noop(void) { }
 void __init x86_init_uint_noop(unsigned int unused) { }
-int __init iommu_init_noop(void) { return 0; }
-void iommu_shutdown_noop(void) { }
-bool __init bool_x86_init_noop(void) { return false; }
-void x86_op_int_noop(int cpu) { }
-u64 u64_x86_init_noop(void) { return 0; }
+static int __init iommu_init_noop(void) { return 0; }
+static void iommu_shutdown_noop(void) { }
+static bool __init bool_x86_init_noop(void) { return false; }
+static void x86_op_int_noop(int cpu) { }
+static u64 u64_x86_init_noop(void) { return 0; }
 
 /*
  * The platform setup functions are preset with the default functions