fix(st-regulator): enclose macro parameters in parentheses

This corrects MISRA C2012-20.7:
Expressions resulting from the expansion of macro parameters shall be
enclosed in parentheses.

Signed-off-by: Yann Gautier <yann.gautier@st.com>
Change-Id: I9989a5aaacf17f6f7a65381c8d41f21a35f6ddd9
1 file changed