asm-generic: add linux/types.h to cmpxchg.h

Builds of the openrisc or1ksim_defconfig show the following:

  In file included from arch/openrisc/include/generated/asm/cmpxchg.h:1:0,
                   from include/asm-generic/atomic.h:18,
                   from arch/openrisc/include/generated/asm/atomic.h:1,
                   from include/linux/atomic.h:4,
                   from include/linux/dcache.h:4,
                   from fs/notify/fsnotify.c:19:
  include/asm-generic/cmpxchg.h: In function '__xchg':
  include/asm-generic/cmpxchg.h:34:20: error: expected ')' before 'u8'
  include/asm-generic/cmpxchg.h:34:20: warning: type defaults to 'int' in type name

and many more lines of similar errors.  It seems specific to the or32
because most other platforms have an arch specific component that would
have already included types.h ahead of time, but the o32 does not.

Cc: Arnd Bergmann <[email protected]>
Cc: Jonas Bonn <[email protected]>
Signed-off-by: Paul Gortmaker <[email protected]>
Acked-by: David Howells <[email protected]
Signed-off-by: Linus Torvalds <[email protected]>

include/asm-generic/cmpxchg.h

@@ -10,6 +10,7 @@
 #error "Cannot use generic cmpxchg on SMP"
 #endif
 
+#include <linux/types.h>
 #include <linux/irqflags.h>
 
 #ifndef xchg