libpayload: Catch null-pointer dereference in xHCI

Fix a possible null-pointer dereference (hopefully) before anyone runs
into this. Also don't switch ports to xHCI if initialization failed.

Change-Id: I5dbaeb435a98ead0b50d27fde13c9f1433ea3e81
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: http://review.coreboot.org/6245
Tested-by: build bot (Jenkins)
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
1 file changed