Add #includes needed to permit the removal of asm/system.h

asm/system.h is a cause of circular dependency problems because it contains
commonly used primitive stuff like barrier definitions and uncommonly used
stuff like switch_to() that might require MMU definitions.

asm/system.h has been disintegrated by this point on all arches into the
following common segments:

 (1) asm/barrier.h

     Moved memory barrier definitions here.

 (2) asm/cmpxchg.h

     Moved xchg() and cmpxchg() here.  #included in asm/atomic.h.

 (3) asm/bug.h

     Moved die() and similar here.

 (4) asm/exec.h

     Moved arch_align_stack() here.

 (5) asm/elf.h

     Moved AT_VECTOR_SIZE_ARCH here.

 (6) asm/switch_to.h

     Moved switch_to() here.

Signed-off-by: David Howells <dhowells@redhat.com>
diff --git a/include/asm-generic/bitops/atomic.h b/include/asm-generic/bitops/atomic.h
index ecc44a8..9ae6c34 100644
--- a/include/asm-generic/bitops/atomic.h
+++ b/include/asm-generic/bitops/atomic.h
@@ -2,7 +2,7 @@
 #define _ASM_GENERIC_BITOPS_ATOMIC_H_
 
 #include <asm/types.h>
-#include <asm/system.h>
+#include <linux/irqflags.h>
 
 #ifdef CONFIG_SMP
 #include <asm/spinlock.h>