install-build-deps: Remove dpkg armhf architecture

No armhf binary packages are needed, so this CL removes 'dpkg
--add-architecture armhf'.  Only armhf cross-compiler tools are needed
(for the host architecture).

R=dpranke@chromium.org

Review-Url: https://codereview.chromium.org/2901093008
Cr-Original-Commit-Position: refs/heads/master@{#474529}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: ebf58c8008b059bbad0dee9d61f147b9cb85fcd0

install-build-deps.sh

@@ -601,9 +601,6 @@ fi
 
 if test "$do_inst_lib32" = "1" || test "$do_inst_nacl" = "1"; then
   sudo dpkg --add-architecture i386
-  if [[ $distro_id == "Debian" ]]; then
-      sudo dpkg --add-architecture armhf
-  fi
 fi
 sudo apt-get update