clk: qcom: Use regmap_update_bits() to update the clock flags

Currently clk_cbcr_set_flags() reads the CBCR register content,
modifies the flags and writes back the updated value into it.
Sometimes clk_set_flags() gets invoked for the same clock
while clk_enable() is in progress causing the CLK_ENABLE bit
getting updated outside of clk_enable() path. Therefore, use
regmap_update_bits() to update the flags in CBCR register.
Also add a barrier in clock enable/disable path to make
sure that register write goes through.

Change-Id: I8018f8033d05273320fd92cc7d21fcdce0885dfc
Signed-off-by: Odelu Kukatla <okukatla@codeaurora.org>