target/i386: sev: fix failed message typos

In these multiline messages, there were typos. Fix them -- add a missing
space and remove a superfluous apostrophe.

Inspired by Tom's patch.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: qemu-trivial@nongnu.org
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Message-Id: <20190719104118.17735-1-jslaby@suse.cz>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>