arm64: fix midr range for Cortex-A57 erratum 832075

Register MIDR_EL1 is masked to get variant and revision fields, then
compared against midr_range_min and midr_range_max when checking
whether CPU is affected by any particular erratum. However, variant
and revision fields in MIDR_EL1 are separated by 16 bits, so the min
and max of midr range should be constructed accordingly, otherwise
the patch will not be applied when variant field is non-0.

Cc: stable@vger.kernel.org # 3.19+
Acked-by: NAndre Przywara <andre.przywara@arm.com>
Reviewed-by: NPaul Walmsley <paul@pwsan.com>
Signed-off-by: NBo Yan <byan@nvidia.com>
[will: use MIDR_VARIANT_SHIFT to construct upper bound]
Signed-off-by: NWill Deacon <will.deacon@arm.com>

arch/arm64/kernel/cpu_errata.c

@@ -70,7 +70,8 @@ const struct arm64_cpu_capabilities arm64_errata[] = {
 	/* Cortex-A57 r0p0 - r1p2 */
 		.desc = "ARM erratum 832075",
 		.capability = ARM64_WORKAROUND_DEVICE_LOAD_ACQUIRE,
-		MIDR_RANGE(MIDR_CORTEX_A57, 0x00, 0x12),
+		MIDR_RANGE(MIDR_CORTEX_A57, 0x00,
+			   (1 << MIDR_VARIANT_SHIFT) | 2),
 	},
 #endif
 #ifdef CONFIG_ARM64_ERRATUM_845719