mmu: ensure gperf data is mapped

Page tables created at build time may not include the
gperf data at the very end of RAM. Ensure this is mapped
properly at runtime to work around this.

Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
diff --git a/kernel/include/kernel_internal.h b/kernel/include/kernel_internal.h
index 3e0c4f2..702d5c5 100644
--- a/kernel/include/kernel_internal.h
+++ b/kernel/include/kernel_internal.h
@@ -197,6 +197,9 @@
  */
 void z_mem_manage_init(void);
 
+/* Workaround for build-time page table mapping of the kernel */
+void z_kernel_map_fixup(void);
+
 #ifdef __cplusplus
 }
 #endif