powerpc/kgdb: Fix build failure caused by "kgdb.c: unused variable 'acc'"

'acc' isn't used anywhere and thus triggers gcc warning, which causes
build error with CONFIG_PPC_DISABLE_WERROR=n (default):

  cc1: warnings being treated as errors
  arch/powerpc/kernel/kgdb.c: In function 'gdb_regs_to_pt_regs':
  arch/powerpc/kernel/kgdb.c:289: warning: unused variable 'acc'
  make[1]: *** [arch/powerpc/kernel/kgdb.o] Error 1
Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/kernel/kgdb.c

@@ -282,12 +282,6 @@ void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)
 {
 	unsigned long *ptr = gdb_regs;
 	int reg;
-#ifdef CONFIG_SPE
-	union {
-		u32 v32[2];
-		u64 v64;
-	} acc;
-#endif
 
 	for (reg = 0; reg < 32; reg++)
 		UNPACK64(regs->gpr[reg], ptr);