reset: stm32: Fix bank and offset computation

reset: stm32: Fix bank and offset computation

BITS_PER_LONG is used to represent register's size which is 32.
But when compiled on arch64, BITS_PER_LONG is then equal to 64.

Fix bank and offset computation to make it work on arch32 and
arch64 and ensure that register's size is always equal to 32.

Signed-off-by: Patrice Chotard <patrice.chotard@foss.st.com>
Signed-off-by: Pankaj Dev <pankaj.dev@st.com>
Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>