arm64/mm: define ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT

Set ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT for arm64. This
enables Speculative Page Fault handler.

Change-Id: Ic55bd1993b3af78ddac25867c5f422861079bb27
Signed-off-by: Ganesh Mahendran <opensource.ganesh@gmail.com>
Patch-mainline: linux-mm @ Wed, 2 May 2018 15:54:31
Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 9c01a31..d3988b7 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -112,6 +112,7 @@
 	select SPARSE_IRQ
 	select SYSCTL_EXCEPTION_TRACE
 	select THREAD_INFO_IN_TASK
+	select ARCH_SUPPORTS_SPECULATIVE_PAGE_FAULT
 	help
 	  ARM 64-bit (AArch64) Linux support.