xen/arm: domain_build: Panic message should end with a newline

xen/arm: domain_build: Panic message should end with a newline

Since commit 25eb5eec79 "xen: Fix inconsistent callers of panic()" all
the panic message should end with a newline. Unfortunately, some
commits pushed afterwards does not follow the rule.

Modify the offending panic messages to avoid more inconsistency.

Signed-off-by: Julien Grall <julien.grall@arm.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Release-acked-by: Juergen Gross <jgross@suse.com>