mem-ruby: Remove inexistent functions from Util

mem-ruby: Remove inexistent functions from Util

Remove forward declaration of inexistent functions from RubySlicc_Util.sm.

Change-Id: I548bd75cb570371fbdaccf914c5eb9a7b92313d1
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/21086
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Reviewed-by: Anthony Gutierrez <anthony.gutierrez@amd.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>
Tested-by: kokoro <noreply+kokoro@google.com>