Tegra: include flowctlr driver from SoC specific makefiles

The Flow Controller hardware block is not present across all Tegra
SoCs, hence include the driver files from SoC specific makefiles.

T132/T210 are the SoCs which include this hardware block while future
SoCs have removed it.

Change-Id: Iaca25766a4fa51567293d10cf14dae968b0fae80
Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>
diff --git a/plat/nvidia/tegra/soc/t210/platform_t210.mk b/plat/nvidia/tegra/soc/t210/platform_t210.mk
index 5001629..f58baaf 100644
--- a/plat/nvidia/tegra/soc/t210/platform_t210.mk
+++ b/plat/nvidia/tegra/soc/t210/platform_t210.mk
@@ -54,6 +54,7 @@
 
 BL31_SOURCES		+=	lib/cpus/aarch64/cortex_a53.S		\
 				lib/cpus/aarch64/cortex_a57.S		\
+				${COMMON_DIR}/drivers/flowctrl/flowctrl.c	\
 				${SOC_DIR}/plat_psci_handlers.c		\
 				${SOC_DIR}/plat_setup.c			\
 				${SOC_DIR}/plat_secondary.c