clk: Provide OF helper to mark clocks as CRITICAL

This call matches clocks which have been marked as critical in DT
and sets the appropriate flag.  These flags can then be used to
mark the clock core flags appropriately prior to registration.

Legacy bindings requiring this feature must add the clock-critical
property to their binding descriptions, as it is not a part of
common-clock binding.

Cc: devicetree@vger.kernel.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Michael Turquette <mturquette@baylibre.com>
Link: lkml.kernel.org/r/1455225554-13267-4-git-send-email-mturquette@baylibre.com
(cherry picked from commit d56f8994b6fb928f59481fabc25bcd1c2f9bd06d)
[tdas@codeaurora.org: resolve trivial conflict]
Git-commit: d56f8994b6fb928f59481fabc25bcd1c2f9bd06d
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git



Change-Id: I2bf824bd2446ca87baabd31c166119d6c5c90643
Signed-off-by: Taniya Das <tdas@codeaurora.org>