MN10300: Save frame pointer in thread_info struct rather than global var

Save the current exception frame pointer in the thread_info struct rather than
in a global variable as the latter makes SMP tricky, especially when preemption
is also enabled.

This also replaces __frame with current_frame() and rearranges header file
inclusions to make it all compile.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Akira Takeuchi <takeuchi.akr@jp.panasonic.com>

mm/maccess.c

@@ -1,9 +1,9 @@
 /*
  * Access kernel memory without faulting.
  */
-#include <linux/uaccess.h>
 #include <linux/module.h>
 #include <linux/mm.h>
+#include <linux/uaccess.h>
 
 /**
  * probe_kernel_read(): safely attempt to read from a location