fastmodel: use global option 'num_jobs' instead of hardcoded number

Change-Id: I2d3f0855c8475cd44b1012fddf6b695621b2347f
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/58689
Reviewed-by: Gabe Black <gabe.black@gmail.com>
Maintainer: Gabe Black <gabe.black@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
1 file changed