media: i2c: tvp5150: Use parentheses for sizeof

This patch resolves a checkpatch.pl warning:
    WARNING: sizeof *cap should be sizeof(*cap)

Signed-off-by: Nasser Afshin <Afshin.Nasser@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>