x86/mm/pti: Make local symbols static

With 'make C=2 W=1', sparse and gcc both complain:

  CHECK   arch/x86/mm/pti.c
arch/x86/mm/pti.c:84:3: warning: symbol 'pti_mode' was not declared. Should it be static?
arch/x86/mm/pti.c:605:6: warning: symbol 'pti_set_kernel_image_nonglobal' was not declared. Should it be static?
  CC      arch/x86/mm/pti.o
arch/x86/mm/pti.c:605:6: warning: no previous prototype for 'pti_set_kernel_image_nonglobal' [-Wmissing-prototypes]
  605 | void pti_set_kernel_image_nonglobal(void)
      |      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

pti_set_kernel_image_nonglobal() is only used locally. 'pti_mode' exists in
drivers/hwtracing/intel_th/pti.c as well, but it's a completely unrelated
local (static) symbol.

Make both static.
Signed-off-by: Valdis Kletnieks <valdis.kletnieks@vt.edu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lkml.kernel.org/r/27680.1552376873@turing-police

arch/x86/mm/pti.c

@@ -77,7 +77,7 @@ static void __init pti_print_if_secure(const char *reason)
 		pr_info("%s\n", reason);
 }
 
-enum pti_mode {
+static enum pti_mode {
 	PTI_AUTO = 0,
 	PTI_FORCE_OFF,
 	PTI_FORCE_ON
@@ -602,7 +602,7 @@ static void pti_clone_kernel_text(void)
 	set_memory_global(start, (end_global - start) >> PAGE_SHIFT);
 }
 
-void pti_set_kernel_image_nonglobal(void)
+static void pti_set_kernel_image_nonglobal(void)
 {
 	/*
 	 * The identity map is created with PMDs, regardless of the