media: ddbridge/mci: rename defines and fix i/q var types

Adjustments to match the FPGA firmware, and the signal I/Q values are
reported as s16 types from the card firmware.

Picked up from the upstream dddvb GIT.

Signed-off-by: Daniel Scheller <d.scheller@gmx.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>