atomic-long: Fix warnings on arm64

Several inline functions in this file reference undefined functions in
U-Boot.  For example:

atomic-long.h:73:9: warning: implicit declaration of function
'atomic64_sub_and_test'
atomic-long.h:80:9: warning: implicit declaration of function
'atomic64_dec_and_test'
atomic-long.h:87:9: warning: implicit declaration of function
'atomic64_inc_and_test'

Handle this the same as the 32 bit build by wrapping these functions in
a __UBOOT__ check.
Signed-off-by: NBradley Bolen <bradleybolen@gmail.com>

include/asm-generic/atomic-long.h

@@ -66,6 +66,7 @@ static inline void atomic_long_sub(long i, atomic_long_t *l)
 	atomic64_sub(i, v);
 }
 
+#ifndef __UBOOT__
 static inline int atomic_long_sub_and_test(long i, atomic_long_t *l)
 {
 	atomic64_t *v = (atomic64_t *)l;
@@ -135,6 +136,7 @@ static inline long atomic_long_add_unless(atomic_long_t *l, long a, long u)
 	(atomic64_cmpxchg((atomic64_t *)(l), (old), (new)))
 #define atomic_long_xchg(v, new) \
 	(atomic64_xchg((atomic64_t *)(v), (new)))
+#endif  /*  __UBOOT__ */
 
 #else  /*  BITS_PER_LONG == 64  */