powerpc: Uncomment and make enable_kernel_vsx() routine available

enable_kernel_vsx() function was commented since anything was using
it. However, vmx-crypto driver uses VSX instructions which are
only available if VSX is enable. Otherwise it rises an exception oops.

This patch uncomment enable_kernel_vsx() routine and makes it available.
Signed-off-by: Leonidas S. Barbosa <leosilva@linux.vnet.ibm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

arch/powerpc/include/asm/switch_to.h

@@ -29,6 +29,7 @@ static inline void save_early_sprs(struct thread_struct *prev) {}
 
 extern void enable_kernel_fp(void);
 extern void enable_kernel_altivec(void);
+extern void enable_kernel_vsx(void);
 extern int emulate_altivec(struct pt_regs *);
 extern void __giveup_vsx(struct task_struct *);
 extern void giveup_vsx(struct task_struct *);

arch/powerpc/kernel/process.c

@@ -204,8 +204,6 @@ EXPORT_SYMBOL_GPL(flush_altivec_to_thread);
 #endif /* CONFIG_ALTIVEC */
 
 #ifdef CONFIG_VSX
-#if 0
-/* not currently used, but some crazy RAID module might want to later */
 void enable_kernel_vsx(void)
 {
 	WARN_ON(preemptible());
@@ -220,7 +218,6 @@ void enable_kernel_vsx(void)
 #endif /* CONFIG_SMP */
 }
 EXPORT_SYMBOL(enable_kernel_vsx);
-#endif
 
 void giveup_vsx(struct task_struct *tsk)
 {