media: staging: media: omap4iss: code style - avoid macro argument precedence issues

This patch fixes the following checkpatch.pl check:

CHECK: Macro argument 'i' may be better as '(i)' to avoid precedence issues

in file iss_regs.h

Link: https://lore.kernel.org/linux-media/20210221195308.1451-1-knv418@gmail.com


Signed-off-by: Nikolay Kyx <knv418@gmail.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>