[PATCH v2] include/linux: Add missing include / fix build failure

["Peter Hüwe" <PeterHuewe@gmx.de>]

From: Peter Huewe <peterhuewe@gmx.de>

This patch fixes a build failure[1-2] by adding the missing asm/memory.h
include needed for arch_is_coherent().

Error message:
In file included from include/linux/list_bl.h:5,
                 from include/linux/rculist_bl.h:7,
                 from include/linux/dcache.h:7,
                 from include/linux/fs.h:381,
                 from arch/arm/mm/mmap.c:4:
include/linux/bit_spinlock.h: In function 'bit_spin_unlock':
include/linux/bit_spinlock.h:61: error: implicit declaration of function 
'arch_is_coherent'

KernelVersion: linux-next-20101215
Used configs: hackkit_defconfig (arm), ep93xx_defconfig (arm)

References:
[1] http://kisskb.ellerman.id.au/kisskb/buildresult/3651495/
[2] http://kisskb.ellerman.id.au/kisskb/buildresult/3651425/

Signed-off-by: Peter Huewe <peterhuewe@gmx.de>
---
v2:
moved additional information in the commit message.

 include/linux/bit_spinlock.h |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/include/linux/bit_spinlock.h b/include/linux/bit_spinlock.h
index e612575..053fad7 100644
--- a/include/linux/bit_spinlock.h
+++ b/include/linux/bit_spinlock.h
@@ -4,6 +4,7 @@
 #include <linux/kernel.h>
 #include <linux/preempt.h>
 #include <asm/atomic.h>
+#include <asm/memory.h>
 
 /*
  *  bit-based spin_lock()
-- 
1.7.2.2