Disable workaround for CVE-2017-5715 on unaffected platforms

Change-Id: Ib67b841ab621ca1ace3280e44cf3e1d83052cb73
Signed-off-by: Dimitris Papastamos <dimitris.papastamos@arm.com>
diff --git a/plat/rpi3/platform.mk b/plat/rpi3/platform.mk
index 821f801..e201cee 100644
--- a/plat/rpi3/platform.mk
+++ b/plat/rpi3/platform.mk
@@ -64,6 +64,8 @@
 ERRATA_A53_843419		:= 1
 ERRATA_A53_855873		:= 1
 
+WORKAROUND_CVE_2017_5715	:= 0
+
 # Disable the PSCI platform compatibility layer by default
 ENABLE_PLAT_COMPAT		:= 0