misc: Substitute pointer to Request with aliased RequestPtr

Every usage of Request* in the code has been replaced with the
RequestPtr alias.  This is a preparing patch for when RequestPtr will be
the typdefed to a smart pointer to Request rather then a raw pointer to
Request.

Change-Id: I73cbaf2d96ea9313a590cdc731a25662950cd51a
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/10995
Reviewed-by: Anthony Gutierrez <anthony.gutierrez@amd.com>
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Maintainer: Anthony Gutierrez <anthony.gutierrez@amd.com>

src/cpu/simple/base.cc

@@ -468,7 +468,7 @@ BaseSimpleCPU::checkForInterrupts()
 
 
 void
-BaseSimpleCPU::setupFetchRequest(Request *req)
+BaseSimpleCPU::setupFetchRequest(RequestPtr req)
 {
     SimpleExecContext &t_info = *threadInfo[curThread];
     SimpleThread* thread = t_info.thread;