[PARISC] PA7200 also supports prefetch for read

It seems PA7200 processors also suppress traps on loads to
%r0. This means we can prefetch for read on these cpus. Of course,
we can't support prefetch for write, since that requires
LOAD DOUBLEWORD which was added with PA2.0
Signed-off-by: Kyle McMartin <kyle@parisc-linux.org>

arch/parisc/Kconfig

@@ -127,7 +127,7 @@ config PA11
 
 config PREFETCH
 	def_bool y
-	depends on PA8X00
+	depends on PA8X00 || PA7200
 
 config 64BIT
 	bool "64-bit kernel"

include/asm-parisc/prefetch.h

@@ -24,11 +24,14 @@ extern inline void prefetch(const void *addr)
 	__asm__("ldw 0(%0), %%r0" : : "r" (addr));
 }
 
+/* LDD is a PA2.0 addition. */
+#ifdef CONFIG_PA20
 #define ARCH_HAS_PREFETCHW
 extern inline void prefetchw(const void *addr)
 {
 	__asm__("ldd 0(%0), %%r0" : : "r" (addr));
 }
+#endif /* CONFIG_PA20 */
 
 #endif /* CONFIG_PREFETCH */
 #endif /* __ASSEMBLY__ */