sinowealth: use a union instead of doing pointer arithmetic on DPI slots
sinowealth: use a union instead of doing pointer arithmetic on DPI slots

This makes the code a bit more self-explaining and less error-prone as
we don't have to think about memory addresses when modifying DPI.
Also fixes several `bugprone-implicit-widening-of-multiplication-result`
clang-tidy warnings.

libratbag/libratbag,libratbag/libratbag,libratbag/libratbag