powerpc/44x/uic: Consolidate chained IRQ handler install/remove

The driver currently sets the handler data and the chained handler in
two separate steps. This creates a theoretical race window where an
interrupt could fire after the handler is set but before the data is
assigned, leading to a NULL pointer dereference.

Replace the two calls with irq_set_chained_handler_and_data() to set
both the handler and its data atomically under the irq_desc->lock.

Signed-off-by: Chen Ni <nichen@iscas.ac.cn>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20260119063507.940782-1-nichen@iscas.ac.cn

Author: Chen Ni

arch/powerpc/platforms/44x/uic.c

@@ -309,8 +309,8 @@ void __init uic_init_tree(void)
 
 			cascade_virq = irq_of_parse_and_map(np, 0);
 
-			irq_set_handler_data(cascade_virq, uic);
-			irq_set_chained_handler(cascade_virq, uic_irq_cascade);
+			irq_set_chained_handler_and_data(cascade_virq,
+							 uic_irq_cascade, uic);
 
 			/* FIXME: setup critical cascade?? */
 		}