cpu: Remove units from stats description

cpu: Remove units from stats description

A recent change https://gem5-review.googlesource.com/c/public/gem5/+/40622
allows units to be shown in stats dump; the units in stats
descriptions are nolonger necessary. This change removes units
from stats descriptions. However, for units that are multiples
of a supported unit (e.g. MegaBytes), the units

Change-Id: Ib63ea44e757f755f761b20b40e045bc37c90baff
Signed-off-by: Hoa Nguyen <hoanguyen@ucdavis.edu>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/40735
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Maintainer: Gabe Black <gabe.black@gmail.com>