powerpc/fault: Unnest definition of page_fault_is_write() and page_fault_is_bad()

To make it more readable, separate page_fault_is_write() and page_fault_is_bad()
to avoir several levels of #ifdefs
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/6afaac2495248d68f94c438c5ec36b6010931de5.1607491748.git.christophe.leroy@csgroup.eu

arch/powerpc/mm/fault.c

@@ -363,17 +363,19 @@ static void sanity_check_fault(bool is_write, bool is_user,
  */
 #if (defined(CONFIG_4xx) || defined(CONFIG_BOOKE))
 #define page_fault_is_write(__err)	((__err) & ESR_DST)
-#define page_fault_is_bad(__err)	(0)
 #else
 #define page_fault_is_write(__err)	((__err) & DSISR_ISSTORE)
-#if defined(CONFIG_PPC_8xx)
+#endif
+
+#if defined(CONFIG_4xx) || defined(CONFIG_BOOKE)
+#define page_fault_is_bad(__err)	(0)
+#elif defined(CONFIG_PPC_8xx)
 #define page_fault_is_bad(__err)	((__err) & DSISR_NOEXEC_OR_G)
 #elif defined(CONFIG_PPC64)
 #define page_fault_is_bad(__err)	((__err) & DSISR_BAD_FAULT_64S)
 #else
 #define page_fault_is_bad(__err)	((__err) & DSISR_BAD_FAULT_32S)
 #endif
-#endif
 
 /*
  * For 600- and 800-family processors, the error_code parameter is DSISR