x86/emul: Clean up the naming of the retire union

x86/emul: Clean up the naming of the retire union

Rename byte to raw, as the field being a single byte long is an implementation
detail.  Make the bitfields part of an anonymous struct to remove the .flags
qualifier.  Change the types of the flags to being booleans, to match their
use.

No functional change.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>