serial: fsl_lpuart: add earlycon support

Add support for DT and command line based earlycon support for
lpuart and lpuart32 used on Freescale Vybrid and and QorIQ LS1021A
processors.

Signed-off-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/kernel-parameters.txt

@@ -1023,6 +1023,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			serial port must already be setup and configured.
 			Options are not yet supported.
 
+		lpuart,<addr>
+		lpuart32,<addr>
+			Use early console provided by Freescale LP UART driver
+			found on Freescale Vybrid and QorIQ LS1021A processors.
+			A valid base address must be provided, and the serial
+			port must already be setup and configured.
+
 	earlyprintk=	[X86,SH,BLACKFIN,ARM,M68k]
 			earlyprintk=vga
 			earlyprintk=efi