[POWERPC] Early debug forces console log level to max

This makes the early debug option force the console loglevel
to the max.  The early debug option is meant to catch messages very
early in the kernel boot process, in many cases, before the kernel
has a chance to parse the "debug" command line argument.  Thus it
makes sense when CONFIG_PPC_EARLY_DEBUG is set, to force the console
log level to the max at boot time.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>