powerpc: implement arch_xor_unlock_is_negative_byte on 32-bit

Simply remove the ifdef.  The assembly is identical to that in the
non-optimised case of test_and_clear_bits() on PPC32, and it's not clear
to me how the PPC32 optimisation works, nor whether it would work for
arch_xor_unlock_is_negative_byte().  If that optimisation would work,
someone can implement it later, but this is more efficient than the
implementation in filemap.c.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
Cc: Albert Ou <[email protected]>
Cc: Alexander Gordeev <[email protected]>
Cc: Andreas Dilger <[email protected]>
Cc: Christian Borntraeger <[email protected]>
Cc: Christophe Leroy <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Ivan Kokshaysky <[email protected]>
Cc: Matt Turner <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Palmer Dabbelt <[email protected]>
Cc: Paul Walmsley <[email protected]>
Cc: Richard Henderson <[email protected]>
Cc: Sven Schnelle <[email protected]>
Cc: "Theodore Ts'o" <[email protected]>
Cc: Thomas Bogendoerfer <[email protected]>
Cc: Vasily Gorbik <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: Matthew Wilcox (Oracle)

arch/powerpc/include/asm/bitops.h

@@ -233,7 +233,6 @@ static inline int arch_test_and_change_bit(unsigned long nr,
 	return test_and_change_bits(BIT_MASK(nr), addr + BIT_WORD(nr)) != 0;
 }
 
-#ifdef CONFIG_PPC64
 static inline bool arch_xor_unlock_is_negative_byte(unsigned long mask,
 		volatile unsigned long *p)
 {
@@ -251,11 +250,8 @@ static inline bool arch_xor_unlock_is_negative_byte(unsigned long mask,
 
 	return (old & BIT_MASK(7)) != 0;
 }
-
 #define arch_xor_unlock_is_negative_byte arch_xor_unlock_is_negative_byte
 
-#endif /* CONFIG_PPC64 */
-
 #include <asm-generic/bitops/non-atomic.h>
 
 static inline void arch___clear_bit_unlock(int nr, volatile unsigned long *addr)