powerpc: Fix alignment of secondary cpu spin vars

Commit 5c0484e25ec0 ('powerpc: Endian safe trampoline') resulted in
losing proper alignment of the spinlock variables used when booting
secondary CPUs, causing some quite odd issues with failing to boot on
PA Semi-based systems.

This showed itself on ppc64_defconfig, but not on pasemi_defconfig,
so it had gone unnoticed when I initially tested the LE patch set.

Fix is to add explicit alignment instead of relying on good luck. :)

[ It appears that there is a different issue with PA Semi systems
  however this fix is definitely correct so applying anyway -- BenH
]

Fixes: 5c0484e25ec0 ('powerpc: Endian safe trampoline')
Reported-by: Christian Zigotzky <chzigotzky@xenosoft.de>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=67811
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/kernel/head_64.S

@@ -80,6 +80,7 @@ END_FTR_SECTION(0, 1)
 	 * of the function that the cpu should jump to to continue
 	 * initialization.
 	 */
+	.balign 8
 	.globl  __secondary_hold_spinloop
 __secondary_hold_spinloop:
 	.llong	0x0