kernel: gtod: vsyscall

Introduce kernel user helper vsyscall to allow a higher performance
gettimeofday implementation in user-space.

Change-Id: I9b9971d217382129170ecd6a35461539dac9eebb
Signed-off-by: Brent DeGraaf <bdegraaf@codeaurora.org>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 5d5f9de..39cf293 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -264,6 +264,13 @@
 	def_bool y
 	depends on BUG
 
+config GENERIC_TIME_VSYSCALL
+	bool "Enable gettimeofday updates"
+	depends on CPU_V7
+	help
+	  Enables updating the kernel user helper area with the xtime struct
+	  data for gettimeofday via kernel user helpers.
+
 source "init/Kconfig"
 
 source "kernel/Kconfig.freezer"