V4L/DVB (8472): cx23885: SRAM changes for the 885 and 887 silicon parts.

In a previous patch I merged both memory maps into a single struct, believing
that they could be combined. We've since found problems with streaming
multiple channels on the 885. I'm restoring the multiple memory map structs
- in line with the windows driver.

Signed-off-by: Steven Toth <stoth@hauppauge.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>