V4L/DVB (9895): cx18: Refine the firmware load and firmware startup process

Refine the firmware load and firmware startup process.  Significant changes
are to ensure the SCB and IPC area are correct before starting up the firmware,
and letting the CPU firmware start up the APU firmware for us.

Signed-off-by: Andy Walls <awalls@radix.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>