dm: core: use s32 instead of int for dev_read_s32_default

dm: core: use s32 instead of int for dev_read_s32_default

dev_read_s32_default is for getting an s32 from a Device Tree property
and allows to take a default value if that property is missing.

Considering it calls ofnode_read_u32_default which takes a u32 and
returns a u32, it should do the same instead of using an int, especially
considering that int size is typically architecture-specific, as opposed
to s32/u32.

s32 and u32 being the same size, dev_read_s32* functions calling
ofnode_read_u32_default shouldn't be an issue (at the type level at
least) as the information will be stored appropriately in 4B regardless
of the sign.

This incidentally matches all other dev_read_*_default functions.

Fixes: a1b17e4f4c82 ("dm: core: Add a function to read into a unsigned int")
Signed-off-by: Quentin Schulz <quentin.schulz@cherry.de>
Reviewed-by: Simon Glass <sjg@chromium.org>