mem-cache: Remove extra cache header from AMAP

mem-cache: Remove extra cache header from AMAP

The cache header was being included in the AMAP, although not
used, which resulted in slightly longer compilation time.

Change-Id: I3654bc719c6b5f558af116addae159301602a3cf
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/17711
Reviewed-by: Javier Bueno Hedo <javier.bueno@metempsy.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>