This patch introduces the 'memconsole' driver.

Our firmware gives us access to an in-memory log of the firmware's
output.   This gives us visibility in a data-center of headless machines
as to what the firmware is doing.

The memory console is found by the driver by finding a header block in
the EBDA.  The buffer is then copied out, and is exported to userland in
the file /sys/firmware/log.
Signed-off-by: NSan Mehat <san@google.com>
Signed-off-by: NMike Waychison <mikew@google.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>