clk: Allow clocks to be marked as CRITICAL

Critical clocks are those which must not be gated, else undefined
or catastrophic failure would occur.  Here we have chosen to
ensure the prepare/enable counts are correctly incremented, so as
not to confuse users with enabled clocks with no visible users.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Michael Turquette <mturquette@baylibre.com>
Link: lkml.kernel.org/r/1455225554-13267-2-git-send-email-mturquette@baylibre.com
(cherry picked from commit 32b9b10961860860268961d9aad0c56a73018c37)
[tdas@codeaurora.org: resolve trivial merge conflict]
Git-commit: 32b9b10961860860268961d9aad0c56a73018c37
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git



Change-Id: I003abf22da8600dd90ef397d293544b4bc9e0160
Signed-off-by: Taniya Das <tdas@codeaurora.org>