tile: change <asm/system.h> to <asm/switch_to.h> in comments

Also fix mentions of it in #error statements.
Signed-off-by: NChris Metcalf <cmetcalf@tilera.com>

arch/tile/kernel/regs_32.S

@@ -20,7 +20,7 @@
 #include <asm/switch_to.h>
 
 /*
- * See <asm/system.h>; called with prev and next task_struct pointers.
+ * See <asm/switch_to.h>; called with prev and next task_struct pointers.
  * "prev" is returned in r0 for _switch_to and also for ret_from_fork.
  *
  * We want to save pc/sp in "prev", and get the new pc/sp from "next".
@@ -39,7 +39,7 @@
  */
 
 #if CALLEE_SAVED_REGS_COUNT != 24
-# error Mismatch between <asm/system.h> and kernel/entry.S
+# error Mismatch between <asm/switch_to.h> and kernel/entry.S
 #endif
 #define FRAME_SIZE ((2 + CALLEE_SAVED_REGS_COUNT) * 4)
 

arch/tile/kernel/regs_64.S

@@ -20,7 +20,7 @@
 #include <asm/switch_to.h>
 
 /*
- * See <asm/system.h>; called with prev and next task_struct pointers.
+ * See <asm/switch_to.h>; called with prev and next task_struct pointers.
  * "prev" is returned in r0 for _switch_to and also for ret_from_fork.
  *
  * We want to save pc/sp in "prev", and get the new pc/sp from "next".
@@ -39,7 +39,7 @@
  */
 
 #if CALLEE_SAVED_REGS_COUNT != 24
-# error Mismatch between <asm/system.h> and kernel/entry.S
+# error Mismatch between <asm/switch_to.h> and kernel/entry.S
 #endif
 #define FRAME_SIZE ((2 + CALLEE_SAVED_REGS_COUNT) * 8)