powerpc: remove the unused function disable_kernel_fp()

The only using of function disable_kernel_fp() was already dropped
in the commit 5daf9071 (powerpc: merge align.c).
Signed-off-by: Kevin Hao <haokexin@gmail.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/include/asm/switch_to.h

@@ -18,7 +18,6 @@ extern struct task_struct *_switch(struct thread_struct *prev,
 
 extern void giveup_fpu(struct task_struct *);
 extern void load_up_fpu(void);
-extern void disable_kernel_fp(void);
 extern void enable_kernel_fp(void);
 extern void flush_fp_to_thread(struct task_struct *);
 extern void enable_kernel_altivec(void);

arch/powerpc/kernel/misc_64.S

@@ -449,19 +449,6 @@ _GLOBAL(scom970_write)
 	blr
 #endif /* CONFIG_CPU_FREQ_PMAC64 || CONFIG_CPU_FREQ_MAPLE */
 
-
-/*
- * disable_kernel_fp()
- * Disable the FPU.
- */
-_GLOBAL(disable_kernel_fp)
-	mfmsr	r3
-	rldicl	r0,r3,(63-MSR_FP_LG),1
-	rldicl	r3,r0,(MSR_FP_LG+1),0
-	mtmsrd	r3			/* disable use of fpu now */
-	isync
-	blr
-
 /* kexec_wait(phys_cpu)
  *
  * wait for the flag to change, indicating this kernel is going away but