soc: qcom: wcnss_ctrl: Introduce local variable "dev"

Introduce a local variable to carry the struct device *, to reduce the
line lengths in the next patch.

Tested-by: Aníbal Limón <anibal.limon@linaro.org>
Link: https://lore.kernel.org/r/20210312003318.3273536-4-bjorn.andersson@linaro.org


Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>