clk: Fix CLK_SET_RATE_GATE flag validation in clk_set_rate().

clk: Fix CLK_SET_RATE_GATE flag validation in clk_set_rate().

The clk_set_rate() code shouldn't check the clock's enable count when
validating CLK_SET_RATE_GATE flag since the enable count could change after
the validation. Similar to clk_set_parent(), it should instead check the
prepare count. The prepare count should go to zero only when the end user
expects the clock to not be enabled in the future. Since the code already
grabs the prepare count before validation, it's not possible for prepare
count to change after validation and by association not possible for a well
behaving end user to enable the clock while the set rate is in progress.

Signed-off-by: Saravana Kannan <skannan@codeaurora.org>
Reviewed-by: Richard Zhao <richard.zhao@freescale.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>