lib: uuid: fix uuid_str_to_le_bin() on 32-bit

lib: uuid: fix uuid_str_to_le_bin() on 32-bit

hextoul() cannot convert a string to a 64-bit number on a 32-bit system.
Use function hextoull() instead.

Reported-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Fixes: 22c48a92cdce ("lib: uuid: supporting building as part of host tools")
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Caleb Connolly <caleb.connolly@linaro.org>
Tested-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>