irqchip/gic-v5: Fix gicv5_its_map_event() ITTE read endianness

Kbuild bot (through sparse) reported that the ITTE read to carry out
a valid check in gicv5_its_map_event() lacks proper endianness handling.

Add the missing endianess conversion.

Fixes: 57d7219 ("irqchip/gic-v5: Add GICv5 ITS support")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Acked-by: Marc Zyngier <maz@kernel.org>
Link: https://patch.msgid.link/20251222102250.435460-1-lpieralisi@kernel.org
Closes: https://lore.kernel.org/oe-kbuild-all/202512131849.30ZRTBeR-lkp@intel.com/

Author: Lorenzo Pieralisi

drivers/irqchip/irq-gic-v5-its.c

@@ -849,7 +849,7 @@ static int gicv5_its_map_event(struct gicv5_its_dev *its_dev, u16 event_id, u32
 
 	itte = gicv5_its_device_get_itte_ref(its_dev, event_id);
 
-	if (FIELD_GET(GICV5_ITTL2E_VALID, *itte))
+	if (FIELD_GET(GICV5_ITTL2E_VALID, le64_to_cpu(*itte)))
 		return -EEXIST;
 
 	itt_entry = FIELD_PREP(GICV5_ITTL2E_LPI_ID, lpi) |