powerpc: Fix compile error for CONFIG_VSX

Fix compile error when CONFIG_VSX is enabled.

arch/powerpc/kernel/signal_64.c: In function 'restore_sigcontext':
arch/powerpc/kernel/signal_64.c:241: error: 'i' undeclared (first use in this function)

Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/kernel/signal_64.c

@@ -167,6 +167,7 @@ static long restore_sigcontext(struct pt_regs *regs, sigset_t *set, int sig,
 #endif
 #ifdef CONFIG_VSX
 	double buf[FP_REGS_SIZE];
+	int i;
 #endif
 	unsigned long err = 0;
 	unsigned long save_r13 = 0;