This patch makes it possible to change uart sleep timeout. New sysfs
entry is added (/sys/devices/platform/serial8250.0/sleep_timeout)

Also default timeout is increased to 5 second to make serial console
more usable.

Original patch was written by Tero Kristo some time ago.
Signed-off-by: Jouni Hogander <jouni.hogander@nokia.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>