V4L/DVB (7268): saa7134: fix: tuner should be loaded before calling saa7134_board_init2()

There are several parts of saa7134_board_init2() that calls tuner modules. We
should first load tuner, otherwise, the commands will fail.

Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>