Document continuous Burst Clock option. With this option Burst Clock, if
enabled, will output continuous clock, otherwise Burst Clock will output
clock only when necessary.
Signed-off-by: Ivan Bornyakov <i.bornyakov@metrotek.ru>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>