Merge remote-tracking branch 'remotes/rth/tags/pull-rx-20200408' into staging

Add fall through comment for Coverity.

# gpg: Signature made Wed 08 Apr 2020 16:28:12 BST
# gpg:                using RSA key 7A481E78868B4DB6A85A05C064DF38E8AF7E215F
# gpg:                issuer "[email protected]"
# gpg: Good signature from "Richard Henderson <[email protected]>" [full]
# Primary key fingerprint: 7A48 1E78 868B 4DB6 A85A  05C0 64DF 38E8 AF7E 215F

* remotes/rth/tags/pull-rx-20200408:
  target/rx/translate: Add missing fall through comment

Signed-off-by: Peter Maydell <[email protected]>