powerpc/85xx: mpc85xx_{ds/rdb} replace BUG_ON() by WARN_ON()

No need to BUG() in case mpic_alloc() fails. Use WARN_ON().
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230408140122.25293-4-pali@kernel.org

arch/powerpc/platforms/85xx/mpc85xx_ds.c

@@ -62,7 +62,9 @@ void __init mpc85xx_ds_pic_init(void)
 
 	mpic = mpic_alloc(NULL, 0, flags, 0, 256, " OpenPIC  ");
 
-	BUG_ON(mpic == NULL);
+	if (WARN_ON(!mpic))
+		return;
+
 	mpic_init(mpic);
 
 #ifdef CONFIG_PPC_I8259

arch/powerpc/platforms/85xx/mpc85xx_rdb.c

@@ -39,7 +39,9 @@ void __init mpc85xx_rdb_pic_init(void)
 
 	mpic = mpic_alloc(NULL, 0, flags, 0, 256, " OpenPIC  ");
 
-	BUG_ON(mpic == NULL);
+	if (WARN_ON(!mpic))
+		return;
+
 	mpic_init(mpic);
 }