i387: math_state_restore() isn't called from asm

It was marked asmlinkage for some really old and stale legacy reasons.
Fix that and the equally stale comment.

Noticed when debugging the irq_fpu_usable() bugs.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/x86/include/asm/i387.h

@@ -29,7 +29,7 @@ extern unsigned int sig_xstate_size;
 extern void fpu_init(void);
 extern void mxcsr_feature_mask_init(void);
 extern int init_fpu(struct task_struct *child);
-extern asmlinkage void math_state_restore(void);
+extern void math_state_restore(void);
 extern void __math_state_restore(void);
 extern int dump_fpu(struct pt_regs *, struct user_i387_struct *);
 

arch/x86/kernel/traps.c

@@ -599,10 +599,10 @@ void __math_state_restore(void)
  * Careful.. There are problems with IBM-designed IRQ13 behaviour.
  * Don't touch unless you *really* know how it works.
  *
- * Must be called with kernel preemption disabled (in this case,
- * local interrupts are disabled at the call-site in entry.S).
+ * Must be called with kernel preemption disabled (eg with local
+ * local interrupts as in the case of do_device_not_available).
  */
-asmlinkage void math_state_restore(void)
+void math_state_restore(void)
 {
 	struct thread_info *thread = current_thread_info();
 	struct task_struct *tsk = thread->task;