[x86] Fix early print and console initialization

Currently early print can only be sent to VGA consoles.
For headless systems and QEMU over ssh its useless. This
patch adds support for serial port as early print option.
This can be passed as command line argument from grub.

earlyprint=serial@0x3f8,115200,<clock>

Signed-off-by: Himanshu Chauhan <hschauhan@nulltrace.org>
[x86] Fix the serial port address in DTS file.

The current value in dts returns a wong 64-bit which is
out of range for x86 I/O ports.

Signed-off-by: Himanshu Chauhan <hschauhan@nulltrace.org>
[x86] Make serial port as default console in DTS

Serial port is made as default console in DTS. It has
to be overridden from bootcmd for vga.

Changed the sizecell to 0.

Signed-off-by: Himanshu Chauhan <hschauhan@nulltrace.org>