Revert "powerpc: slightly improve cache helpers"

This reverts commit 6c587584.

It triggers a probable compiler bug on clang which leads to crashes.

With GCC it allows the compiler to use a more efficient register
allocation but current GCC versions never do that at any of the current
call sites, so there's no benefit.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/cache.h

@@ -107,22 +107,22 @@ extern void _set_L3CR(unsigned long);
 
 static inline void dcbz(void *addr)
 {
-	__asm__ __volatile__ ("dcbz %y0" : : "Z"(*(u8 *)addr) : "memory");
+	__asm__ __volatile__ ("dcbz 0, %0" : : "r"(addr) : "memory");
 }
 
 static inline void dcbi(void *addr)
 {
-	__asm__ __volatile__ ("dcbi %y0" : : "Z"(*(u8 *)addr) : "memory");
+	__asm__ __volatile__ ("dcbi 0, %0" : : "r"(addr) : "memory");
 }
 
 static inline void dcbf(void *addr)
 {
-	__asm__ __volatile__ ("dcbf %y0" : : "Z"(*(u8 *)addr) : "memory");
+	__asm__ __volatile__ ("dcbf 0, %0" : : "r"(addr) : "memory");
 }
 
 static inline void dcbst(void *addr)
 {
-	__asm__ __volatile__ ("dcbst %y0" : : "Z"(*(u8 *)addr) : "memory");
+	__asm__ __volatile__ ("dcbst 0, %0" : : "r"(addr) : "memory");
 }
 #endif /* !__ASSEMBLY__ */
 #endif /* __KERNEL__ */