Explicitely state the number of registers the SAA7111 has, and use that
defined value where relevant.  This should prevent any future array overrun
like the one I just fixed in the saa7110 driver.

This patch also saves 8 bytes of memory as a side effect, as the register
cache was larger than needed.
Signed-off-by: NJean Delvare <khali@linux-fr.org>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NMauro Carvalho Chehab <mchehab@infradead.org>