vexpress: Disable perf building

Perf is breaking the builds again so am disabling it so we can get
a successful build.

Change-Id: If4cd20d5177eec085b9d52643db61000dc690511
Signed-off-by: Jon Medhurst <tixy@linaro.org>
diff --git a/BoardConfig.mk b/BoardConfig.mk
index 77ac1cf..d7342b1 100644
--- a/BoardConfig.mk
+++ b/BoardConfig.mk
@@ -97,6 +97,7 @@
 CUSTOM_BOOTLOADER_MAKEFILE := device/linaro/vexpress/bootloader.mk
 INSTALLED_KERNEL_TARGET_NAME := zImage
 INSTALLED_RAMDISK_TARGET_NAME := initrd
+INCLUDE_PERF := 0
 
 endif