ARM: modules: don't export cpu_set_pte_ext when !MMU

cpu_set_pte_ext is only guaranteed to be defined when CONFIG_MMU, so
don't export it to modules otherwise.
Signed-off-by: NWill Deacon <will.deacon@arm.com>

arch/arm/mm/proc-syms.c

@@ -17,7 +17,9 @@
 
 #ifndef MULTI_CPU
 EXPORT_SYMBOL(cpu_dcache_clean_area);
+#ifdef CONFIG_MMU
 EXPORT_SYMBOL(cpu_set_pte_ext);
+#endif
 #else
 EXPORT_SYMBOL(processor);
 #endif