dev-arm: Initialize cd_addr in src/dev/arm/smmu_v3_transl.cc

dev-arm: Initialize cd_addr in src/dev/arm/smmu_v3_transl.cc

In src/dev/arm/smmu_v3_transl.cc#L1401, cd_addr might not be
initialized when all if statements fail.

Change-Id: Idf53c07a9b5d52eea488e631f7334d4b566e645a
Signed-off-by: Hoa Nguyen <hoanguyen@ucdavis.edu>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/32015
Reviewed-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Maintainer: Giacomo Travaglini <giacomo.travaglini@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>