exec: Clean up fall back when -mem-path allocation fails

exec: Clean up fall back when -mem-path allocation fails

With -mem-path, qemu_ram_alloc_from_ptr() first tries to allocate
accordingly, but when it fails, it falls back to normal allocation.

The fall back allocation code used to be effectively identical to the
"-mem-path not given" code, until it started to diverge in commit
432d268.  I believe the code still works, but clean it up anyway: drop
the special fall back allocation code, and fall back to the ordinary
"-mem-path not given" code instead.

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Message-id: 1375276272-15988-3-git-send-email-armbru@redhat.com
Signed-off-by: Anthony Liguori <anthony@codemonkey.ws>