irqchip/gic-v3-its: Fix ITT_entry_size accessor

According to ARM IHI 0069C (ID070116), we should use GITS_TYPER's
bits [7:4] as ITT_entry_size instead of [8:4]. Although this is
pretty annoying, it only results in a potential over-allocation
of memory, and nothing bad happens.

Fixes: 3dfa576b ("irqchip/gic-v3-its: Add probing for VLPI properties")
Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
[maz: massaged subject and commit message]
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

include/linux/irqchip/arm-gic-v3.h

@@ -319,7 +319,7 @@
 #define GITS_TYPER_PLPIS		(1UL << 0)
 #define GITS_TYPER_VLPIS		(1UL << 1)
 #define GITS_TYPER_ITT_ENTRY_SIZE_SHIFT	4
-#define GITS_TYPER_ITT_ENTRY_SIZE(r)	((((r) >> GITS_TYPER_ITT_ENTRY_SIZE_SHIFT) & 0x1f) + 1)
+#define GITS_TYPER_ITT_ENTRY_SIZE(r)	((((r) >> GITS_TYPER_ITT_ENTRY_SIZE_SHIFT) & 0xf) + 1)
 #define GITS_TYPER_IDBITS_SHIFT		8
 #define GITS_TYPER_DEVBITS_SHIFT	13
 #define GITS_TYPER_DEVBITS(r)		((((r) >> GITS_TYPER_DEVBITS_SHIFT) & 0x1f) + 1)