MdeModulePkg: AtaAtapiPassThru: select master/slave around DIAG command

MdeModulePkg: AtaAtapiPassThru: select master/slave around DIAG command

Some IDE controllers only update ID fields such as sector information on
specific commands such as the DIAG command.

The master/slave device is therefore selected both before and after
sending the DIAG command; otherwise reading the IDE registers yields the
master's ID fields.

(Reza's patch originally *moved* the master/slave selection from after the
DIAG command before it, however Feng asked for the original master/slave
select to be preserved; effectively making the master/slave select
*bracket* the DIAG command. See this subthread:
<http://thread.gmane.org/gmane.comp.bios.tianocore.devel/10545/focus=10550>.)

Cc: Alexander Graf <agraf@suse.de>
Cc: Reza Jelveh <reza.jelveh@tuhh.de>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Gabriel L. Somlo <somlo@cmu.edu>
Cc: Feng Tian <feng.tian@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Reza Jelveh <reza.jelveh@tuhh.de>
[feng.tian@intel.com: see above]
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Feng Tian <feng.tian@intel.com>
[lersek@redhat.com: updated commit message]
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Feng Tian <feng.tian@intel.com>
Tested-by: Gabriel Somlo <somlo@cmu.edu>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18529 6f19259b-4bc3-4df7-8a09-765794883524