x86/fpu: Make kernel_fpu_disable/enable() static

This allows the compiler to inline them and to eliminate them:

   arch/x86/kernel/fpu/core.o:

   text    data     bss     dec     hex filename
   6741       4       8    6753    1a61 core.o.before
   6716       4       8    6728    1a48 core.o.after

Reviewed-by: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/include/asm/i387.h

@@ -54,10 +54,6 @@ static inline void kernel_fpu_end(void)
 	preempt_enable();
 }
 
-/* Must be called with preempt disabled */
-extern void kernel_fpu_disable(void);
-extern void kernel_fpu_enable(void);
-
 /*
  * Some instructions like VIA's padlock instructions generate a spurious
  * DNA fault but don't modify SSE registers. And these instructions

arch/x86/kernel/fpu/core.c

@@ -9,13 +9,13 @@
 
 static DEFINE_PER_CPU(bool, in_kernel_fpu);
 
-void kernel_fpu_disable(void)
+static void kernel_fpu_disable(void)
 {
 	WARN_ON(this_cpu_read(in_kernel_fpu));
 	this_cpu_write(in_kernel_fpu, true);
 }
 
-void kernel_fpu_enable(void)
+static void kernel_fpu_enable(void)
 {
 	this_cpu_write(in_kernel_fpu, false);
 }
@@ -32,7 +32,7 @@ void kernel_fpu_enable(void)
  * Except for the eagerfpu case when we return true; in the likely case
  * the thread has FPU but we are not going to set/clear TS.
  */
-static inline bool interrupted_kernel_fpu_idle(void)
+static bool interrupted_kernel_fpu_idle(void)
 {
 	if (this_cpu_read(in_kernel_fpu))
 		return false;
@@ -52,7 +52,7 @@ static inline bool interrupted_kernel_fpu_idle(void)
  * in an interrupt context from user mode - we'll just
  * save the FPU state as required.
  */
-static inline bool interrupted_user_mode(void)
+static bool interrupted_user_mode(void)
 {
 	struct pt_regs *regs = get_irq_regs();
 	return regs && user_mode(regs);