[WATCHDOG] mpc8xxx_wdt: various renames, mostly s/mpc83xx/mpc8xxx/g

mpc83xx_wdt.c renamed to mpc8xxx_wdt.c, now we can do various renames in
the file itself.

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Cc: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>