x86/reboot: Add quirk to make Dell C6100 use reboot=pci automatically

Dell PowerEdge C6100 machines fail to completely reboot about 20% of the time.

Signed-off-by: Masoud Sharbiani <msharbiani@twitter.com>
Signed-off-by: Vinson Lee <vlee@twitter.com>
Cc: Robin Holt <holt@sgi.com>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/1379717947-18042-1-git-send-email-vlee@freedesktop.org


Signed-off-by: Ingo Molnar <mingo@kernel.org>