posix: pthread: fix `zephyr_to_posix_priority` assert test

If `z_prio` is negative and we want to make sure that it is
within `[-CONFIG_NUM_COOP_PRIORITIES, -1]`, we should invert
its sign and make sure that it is `<=`
`CONFIG_NUM_COOP_PRIORITIES` instead of `<`.

Signed-off-by: Yong Cong Sin <ycsin@meta.com>
1 file changed