scons: Added channel_addr.cc dependency to channel_addr GTest

scons: Added channel_addr.cc dependency to channel_addr GTest

In some circumstances not including channel_addr.cc as a dependency for
the channel_addr.test compilation resulted in a build failure (this was
observed in gem5's Kokoro CI system). This commit fixes this problem.

Change-Id: Ic38a104a1e6bf655fc64158b556e6227d5ac3981
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/23603
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>
Tested-by: kokoro <noreply+kokoro@google.com>