[LTP] [Patch] modify sleep usec test condition for pselect01

[bibo m. <bib...@li...>]

Hi,
The original test case has some bug, currently pselect system call sleep
unit can not be nsec unit, it must be multiplier of 1/HZ second. This 
patch modify it.
I post patch before, and I refreshed the patch this time.
Any comment is welcome.

Thanks
Bibo,mao