dev: Remove using namespace std and TheISA from ide_disk.cc.

Neither was necessary since either that namespace wasn't used, or was
used explicitly when referenced.

Change-Id: I96d2791c09250255e7e65d47cbb6f65eb4fcb3ba
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/22267
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>

src/dev/storage/ide_disk.cc

@@ -63,9 +63,6 @@
 #include "sim/core.hh"
 #include "sim/sim_object.hh"
 
-using namespace std;
-using namespace TheISA;
-
 IdeDisk::IdeDisk(const Params *p)
     : SimObject(p), ctrl(NULL), image(p->image), diskDelay(p->delay),
       dmaTransferEvent([this]{ doDmaTransfer(); }, name()),