V4L/DVB (6669): Add few missing bits of code to saa7134_resume

First the saa7134_initdev waits between saa7134_hwinit1
and saa7134_hwinit2 , thus it is probably wise to do the same in saa7134_resume
some hardware probably needs this.

Call saa7134_irq_video_signalchange in .resume like in saa7134_resume to make
saa7134_resume mirror perfectly the saa7134_initdev although
this call isn't strictly necessary in the saa7134_initdev,
but it won't harm anyway.

Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>