staging: st-cec: add parentheses around complex macros

This patch fixes the following checkpatch.pl error:
ERROR: Macros with complex values should be enclosed in parentheses

Signed-off-by: Maninder Singh <maninder.s2@samsung.com>
Acked-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>