mem: Fix whitespace in mem/ruby/system/Sequencer.py.

Some aspects of the formatting in this file were questionable, like
aligning =s between adjacent lines, although not technically against the
style rules as far as I know.

More strangely though, the whole file used three space indents instead
of the typical four.

Change-Id: I7b60f1978c5b2c60a15296b10d09d5701cf7fa5c
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/52108
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
1 file changed