clk: qcom: clk-alpha-pll: replace regval with val

Driver uses regval variable for holding register values, replace with a
shorter one val

Suggested-by: Stephen Boyd <sboyd@kernel.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Link: https://lore.kernel.org/r/20210127070811.152690-2-vkoul@kernel.org
Signed-off-by: Stephen Boyd <sboyd@kernel.org>