fix(st-gpio): define shift as uint32_t

This corrects MISRA C2012-10.6:
The value of a composite expression shall not be assigned to an object
with wider essential type.
While at it change all the shift values to unsigned.

Signed-off-by: Yann Gautier <yann.gautier@st.com>
Change-Id: Idf9915313af965db2106095df7cb48a84f50c519
1 file changed