util: Break up some unit tests in the m5 utility.

util: Break up some unit tests in the m5 utility.

Some unit tests for the inst and semi call types in the m5 utility were
too big and testing multiple scenarioes. This change breaks them up into
individual tests, like in the addr call type unit test.

Change-Id: I764d9edfbe4f6bdcc5907173247f7511c68aa1d0
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/36855
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>