First version of the binding didn't have the eMMC clock. This patch
allows to not registering the eMMC clock if it is not present in the
device tree. Then the device tree can be backwards compatible.
Suggested-by: NStephen Boyd <sboyd@codeaurora.org>
Signed-off-by: NGregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: NUlf Hansson <ulf.hansson@linaro.org>