media: uapi: c3-isp: Fix documentation warning

media: uapi: c3-isp: Fix documentation warning

Building htmldocs generates a warning:

WARNING: include/uapi/linux/media/amlogic/c3-isp-config.h:199
error: Cannot parse struct or union!

Which correctly highlights that the c3_isp_params_block_header symbol
is wrongly documented as a struct while it's a plain #define instead.

Fix this by removing the 'struct' identifier from the documentation of
the c3_isp_params_block_header symbol.

[ribalda: Add Closes:]

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Closes: https://lore.kernel.org/all/20251127131425.4b5b6644@canb.auug.org.au/
Fixes: 45662082855c ("media: uapi: Convert Amlogic C3 to V4L2 extensible params")
Cc: stable@vger.kernel.org
Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>