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

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: 57d72196dfc8 ("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/