asm-generic: rwsem: de-PPCify rwsem.h

asm-generic/rwsem.h used to live under arch/powerpc. During its
liberation to common code, a few references to its former home where
preserved, in particular the definition of RWSEM_ACTIVE_MASK is
predicated on CONFIG_PPC64.

This patch updates the ifdefs and comments to architecturally neutral
versions.
Acked-by: NArnd Bergmann <arnd@arndb.de>
Acked-by: NRichard Kuo <rkuo@codeaurora.org>
Signed-off-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

include/asm-generic/rwsem.h

-#ifndef _ASM_POWERPC_RWSEM_H
-#define _ASM_POWERPC_RWSEM_H
+#ifndef _ASM_GENERIC_RWSEM_H
+#define _ASM_GENERIC_RWSEM_H
 
 #ifndef _LINUX_RWSEM_H
 #error "Please don't include <asm/rwsem.h> directly, use <linux/rwsem.h> instead."
@@ -8,7 +8,7 @@
 #ifdef __KERNEL__
 
 /*
- * R/W semaphores for PPC using the stuff in lib/rwsem.c.
+ * R/W semaphores originally for PPC using the stuff in lib/rwsem.c.
  * Adapted largely from include/asm-i386/rwsem.h
  * by Paul Mackerras <paulus@samba.org>.
  */
@@ -16,7 +16,7 @@
 /*
  * the semaphore definition
  */
-#ifdef CONFIG_PPC64
+#ifdef CONFIG_64BIT
 # define RWSEM_ACTIVE_MASK		0xffffffffL
 #else
 # define RWSEM_ACTIVE_MASK		0x0000ffffL
@@ -129,4 +129,4 @@ static inline long rwsem_atomic_update(long delta, struct rw_semaphore *sem)
 }
 
 #endif	/* __KERNEL__ */
-#endif	/* _ASM_POWERPC_RWSEM_H */
+#endif	/* _ASM_GENERIC_RWSEM_H */