serial: 8250_omap: Add earlycon support for the AM654 UART controller

Currently there is no support for earlycon on the AM654 UART
controller. This commit adds it.

Signed-off-by: Ronald Wahl <ronald.wahl@raritan.com>
Reviewed-by: Vignesh Raghavendra <vigneshr@ti.com>
Link: https://lore.kernel.org/r/20231031131242.15516-1-rwahl@gmx.de


Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>