clk: qcom: gcc-qcs404: Add cfg_offset for blsp1_uart3 clock

The CFG/M/N/D registers are at an offset of 0x20 from the CMD register
only for blsp1_uart3 clock, so add it for uart3 only.

Signed-off-by: Taniya Das <tdas@codeaurora.org>
Signed-off-by: Anu Ramanathan <anur@codeaurora.org>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>