clk: imx: Add check for kcalloc

As the potential failure of the kcalloc(),
it should be better to check it in order to
avoid the dereference of the NULL pointer.

Fixes: 379c9a24cc ("clk: imx: Fix reparenting of UARTs not associated with stdout")
Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
Reviewed-by: Abel Vesa <abel.vesa@nxp.com>
Link: https://lore.kernel.org/r/20220310080257.1988412-1-jiasheng@iscas.ac.cn
Signed-off-by: Abel Vesa <abel.vesa@nxp.com>

drivers/clk/imx/clk.c

@@ -176,6 +176,8 @@ void imx_register_uart_clocks(unsigned int clk_count)
 		int i;
 
 		imx_uart_clocks = kcalloc(clk_count, sizeof(struct clk *), GFP_KERNEL);
+		if (!imx_uart_clocks)
+			return;
 
 		if (!of_stdout)
 			return;