ARM: 9302/1: traps: hide unused functions on NOMMU

A couple of functions in this file are only used on MMU-enabled
builds, and never even declared otherwise, causing these build
warnings:

arch/arm/kernel/traps.c:759:6: error: no previous prototype for '__pte_error' [-Werror=missing-prototypes]
arch/arm/kernel/traps.c:764:6: error: no previous prototype for '__pmd_error' [-Werror=missing-prototypes]
arch/arm/kernel/traps.c:769:6: error: no previous prototype for '__pgd_error' [-Werror=missing-prototypes]

Protect these in an #ifdef to avoid the warnings and save a little
bit of .text space.
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>

arch/arm/kernel/traps.c

@@ -756,6 +756,7 @@ void __readwrite_bug(const char *fn)
 }
 EXPORT_SYMBOL(__readwrite_bug);
 
+#ifdef CONFIG_MMU
 void __pte_error(const char *file, int line, pte_t pte)
 {
 	pr_err("%s:%d: bad pte %08llx.\n", file, line, (long long)pte_val(pte));
@@ -770,6 +771,7 @@ void __pgd_error(const char *file, int line, pgd_t pgd)
 {
 	pr_err("%s:%d: bad pgd %08llx.\n", file, line, (long long)pgd_val(pgd));
 }
+#endif
 
 asmlinkage void __div0(void)
 {