ext2fs: Use the complete random() range in i_gen.

i_gen is unsigned in ext2fs so we can handle the complete
32 bits.

MFC after:	1 week
Fixing incorrect id for Intel Centrino Wireless-N 130.

PR:             kern/180094
Submitted by:   Cedric <cg@cgross.info>
Approved by:    sbruno (mentor)
MFC after:      3 weeks
Adding myself to the calendar!

Approved by:	sbruno (mentor)