[PATCH] powerpc: hvc_console updates

These are some updates from both Ryan and Arnd for the hvc_console
driver:

The main point is to enable the inclusion of a console driver
for rtas, which is currrently needed for the cell platform.

Also shuffle around some data-type declarations and moves some
functions out of include/asm-ppc64/hvconsole.h and into a new
drivers/char/hvc_console.h file.

Signed-off-by: "Ryan S. Arnold" <rsa@us.ibm.com>
Signed-off-by: Arnd Bergmann <abergman@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>