Remove references to defunct _ContextUsrEntryRtn()

This function no longer exists.

Change-Id: I8e4a41b0556e1178b96c64432147d6e1d1bfdcd0
Signed-off-by: Allan Stephens <allan.stephens@windriver.com>

arch/x86/include/nano_private.h

@@ -868,11 +868,6 @@ extern void nanoCpuExcConnect(unsigned int vector,
 			      void (*routine)(NANO_ESF * pEsf),
 			      NANO_EXC_STUB pExcStubMem);
 
-extern void _ContextUsrEntryRtn(_ContextEntry,
-				_ContextArg,
-				_ContextArg,
-				_ContextArg);
-
 extern void _IntVecSet(unsigned int vector,
 		       void (*routine)(void *),
 		       unsigned int dpl);

kernel/nanokernel/nano_context.c

@@ -217,9 +217,6 @@ void _context_exit(tCCS *pContext)
  * can dispense with generating the usual preamble that is only required for
  * functions that actually return.
  *
- * The analogous entry point function for user-mode task contexts is called
- * _ContextUsrEntryRtn().
- *
  * @return Does not return
  *
  * \NOMANUAL