powerpc/xive: Fix section __init warning

xive_spapr_init() is called from a __init routine and calls __init
routines.
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/sysdev/xive/spapr.c

@@ -593,7 +593,7 @@ static bool xive_get_max_prio(u8 *max_prio)
 	return true;
 }
 
-bool xive_spapr_init(void)
+bool __init xive_spapr_init(void)
 {
 	struct device_node *np;
 	struct resource r;