[POWERPC] apm_emu: Use generic apm-emulation

This patch removes a huge amount of code that is now in common code
in drivers/char/apm-emulation.c

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>