arm64: add Cortex-A57 erratum 832075 workaround

The ARM erratum 832075 applies to certain revisions of Cortex-A57,
one of the workarounds is to change device loads into using
load-aquire semantics.
This is achieved using the alternatives framework.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index 92b6ee4..0362f80 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -21,9 +21,10 @@
 #define MAX_CPU_FEATURES	(8 * sizeof(elf_hwcap))
 #define cpu_feature(x)		ilog2(HWCAP_ ## x)
 
-#define ARM64_WORKAROUND_CLEAN_CACHE	0
+#define ARM64_WORKAROUND_CLEAN_CACHE		0
+#define ARM64_WORKAROUND_DEVICE_LOAD_ACQUIRE	1
 
-#define NCAPS				1
+#define NCAPS					2
 
 #ifndef __ASSEMBLY__