pthread: cond: fix pthread_cond_wait always returning ETIMEDOUT
pthread: cond: fix pthread_cond_wait always returning ETIMEDOUT

It was noted that `pthread_cond_wait()` would always return
ETIMEDOUT, even when successful (and no timeout should ever
occur with `K_FOREVER`).

The z_sched_wake() / z_sched_wake_all() / z_sched_wait() API
are used here with a swap return value of 0 to indicate
success.

Fixes #41284

Signed-off-by: Christopher Friedt <76f728c1c3997bf5bfe7e9261eff720c92409a2f@gmail.com>

finikorg/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,finikorg/zephyr,finikorg/zephyr,galak/zephyr,galak/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,finikorg/zephyr