Replace nxsched_self() and nxsched_set_priority() with
standard POSIX sched_getparam() and sched_setparam() in
usb_osal_thread_schedule_other().
This improves portability and follows POSIX standards for
thread priority management.
Change-Id: I2e637268f77e200fbdee3e7713cba1b115976696
Signed-off-by: SunJ <[email protected]>