[XTENSA] Fix modules for non-exec processor configurations

We need to use vmalloc_exec for module loading. Also remove
the definitions MODULE_START and MODULE_END, which wasn't
used, and increase the VMALLOC memory range accordingly.

Signed-off-by: Chris Zankel <chris@zankel.net>
diff --git a/include/asm-xtensa/module.h b/include/asm-xtensa/module.h
index ffb25bf..d9b34be 100644
--- a/include/asm-xtensa/module.h
+++ b/include/asm-xtensa/module.h
@@ -15,9 +15,11 @@
 
 struct mod_arch_specific
 {
-	/* Module support is not completely implemented. */
+	/* No special elements, yet. */
 };
 
+#define MODULE_ARCH_VERMAGIC "xtensa-" __stringify(XCHAL_CORE_ID) " "
+
 #define Elf_Shdr Elf32_Shdr
 #define Elf_Sym Elf32_Sym
 #define Elf_Ehdr Elf32_Ehdr