clk: imx7d: remove UART1 clock setting

There are clock assignments in all i.MX7D dtb files for UART1,
below is the example in imx7d-sdb.dts, so setting UART1 clock
in clock driver is NOT necessary, actually, module clocks setting
should be done in module driver.

&uart1 {
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_uart1>;
	assigned-clocks = <&clks IMX7D_UART1_ROOT_SRC>;
	assigned-clock-parents = <&clks IMX7D_PLL_SYS_MAIN_240M_CLK>;
	status = "okay";
};

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>