MACH-MESON6: Fix section mismatchs

WARNING: arch/arm/mach-meson6/built-in.o(.data+0x1f34): Section mismatch in reference from the variable aml_uart_device to the (unknown reference) .init.data:(unknown)
The variable aml_uart_device references
the (unknown reference) __initdata (unknown)
If the reference is valid then annotate the
variable with __init* or __refdata (see linux/init.h) or name the variable:
*_template, *_timer, *_sht, *_ops, *_probe, *_probe_one, *_console