Add descriptions for RXGK error codes

Also mention what to do when one is received ("abort").

While here, remove the error codes that are not yet relevant and may
never be relevant (COMPOUND_IDENTITY and PRINTED).

Change-Id: I428f89b23499af00ed21486a341271574cf82df3
Fix error table syntax

Change-Id: Id3be1b39b139430a1a6094bfa12b5781ccb6cbc4
Fix enum syntax

Entries are separated by commas, not semicolons.

Change-Id: Ia42158fe3edb5fdfc5ffa746cd36662746aedde1