spapr.c: remove 'out' label in spapr_dt_cas_updates()

'out' can be replaced by 'return' with the appropriate
return value.

CC: David Gibson <david@gibson.dropbear.id.au>
CC: qemu-ppc@nongnu.org
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20200106182425.20312-2-danielhb413@gmail.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>