[NETFILTER]: include/linux/netfilter_bridge.h: header cleanup

Header doesn't use anything from atomic.h.
It fixes headers_check warning:

include/linux/netfilter_bridge.h requires asm/atomic.h, which does not exist

Compile tested on
alpha     arm   i386-up  sparc    sparc64-up  x86_64
alpha-up  i386           sparc64  sparc-up    x86_64-up
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/netfilter_bridge.h

@@ -6,7 +6,6 @@
 
 #include <linux/netfilter.h>
 #if defined(__KERNEL__) && defined(CONFIG_BRIDGE_NETFILTER)
-#include <asm/atomic.h>
 #include <linux/if_ether.h>
 #endif