aarch64: Enable Statistical Profiling Extensions for lower ELs

SPE is only supported in non-secure state.  Accesses to SPE specific
registers from SEL1 will trap to EL3.  During a world switch, before
`TTBR` is modified the SPE profiling buffers are drained.  This is to
avoid a potential invalid memory access in SEL1.

SPE is architecturally specified only for AArch64.

Change-Id: I04a96427d9f9d586c331913d815fdc726855f6b0
Signed-off-by: dp-arm <dimitris.papastamos@arm.com>
diff --git a/include/plat/arm/common/plat_arm.h b/include/plat/arm/common/plat_arm.h
index 62c0ce7..3335b32 100644
--- a/include/plat/arm/common/plat_arm.h
+++ b/include/plat/arm/common/plat_arm.h
@@ -218,4 +218,7 @@
 		uint32_t cookie_lo,
 		void *handle);
 
+/* Disable Statistical Profiling Extensions helper */
+void arm_disable_spe(void);
+
 #endif /* __PLAT_ARM_H__ */