MIPS: loongson32: ls1c: Fix hang during startup

The RTCCTRL reg of LS1C is obselete.
Writing this reg will cause system hang.

Fixes: 60219c563c9b6 ("MIPS: Add RTC support for Loongson1C board")
Signed-off-by: Yang Ling <[e-mail]>
Tested-by: Keguang Zhang <[e-mail]>
Acked-by: Keguang Zhang <[e-mail]>
Signed-off-by: Thomas Bogendoerfer <[e-mail]>

arch/mips/loongson32/ls1c/board.c

···
 static int __init ls1c_platform_init(void)
 {
 	ls1x_serial_set_uartclk(&ls1x_uart_pdev);
-	ls1x_rtc_set_extclk(&ls1x_rtc_pdev);
 
 	return platform_add_devices(ls1c_platform_devices,
 				   ARRAY_SIZE(ls1c_platform_devices));