qtest: Add MMIO support

Introduce [qtest_]{read,write}[bwlq]() libqtest functions and
corresponding QTest protocol commands to replace local versions in
libi2c-omap.c.

Also convert m48t59-test's cmos_{read,write}_mmio() to {read,write}b().

Signed-off-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Andreas Färber <afaerber@suse.de>
Message-id: 1361051043-27944-4-git-send-email-afaerber@suse.de
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>