mem-ruby: Remove bitRemove

mem-ruby: Remove bitRemove

bitRemove is not being used anywhere. If needed, can be used
as src/base/bitfield.hh's bits:

bitRemove(addr, small, big) ==
    ((bits<Addr>(addr, 63, big + 1) << small) |
    bits<Addr>(addr, small, 0))

Change-Id: I45fd3bc0271ccb659d6a94e3dd00ca095dfd6aa7
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/21081
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-by: Anthony Gutierrez <anthony.gutierrez@amd.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>
Tested-by: kokoro <noreply+kokoro@google.com>