sh: Remove old early serial console code V2

Now when the sh-sci driver can do early serial output,
get rid of the old duplicated code. This patch is V2 and
removes support for "earlyprintk=serial" together with
the following kconfig options:
CONFIG_EARLY_SCIF_CONSOLE
CONFIG_EARLY_SCIF_CONSOLE_PORT
CONFIG_EARLY_PRINTK

With this patch applied "earlyprintk=" support is always
built-in the SuperH kernel. For this to work the serial
driver must have early platform support and in the case
of sh-sci the serial console needs to be enabled:
CONFIG_SERIAL_SH_SCI_CONSOLE=y

So after enabling the SuperH SCI console kconfig option
you also need to point out port using the kernel command
line: "earlyprintk=sh-sci.N[,baudrate][,keep]"

Remember that clocks may be disabled by the boot loader
so you may have to do some board specific static clock
setup before earlyprintk will work on your platform.

Signed-off-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>