fix(rcar3-drivers): add integer overflow check

Check against overflows while calculating the "len" variable.

Reviewed-by: Tomer Fichman <Tomer.Fichman@cymotive.com>
Signed-off-by: Yoshifumi Hosoya <yoshifumi.hosoya.wj@renesas.com>
Change-Id: I0c50152a04365c6f52e0db3096e27e8a800c59ea
1 file changed