poplar: Remove unused function prototype

Signed-off-by: Victor Chong <victor.chong@linaro.org>
Tested-by: Shawn Guo <shawn.guo@linaro.org>
diff --git a/plat/hisilicon/poplar/include/plat_private.h b/plat/hisilicon/poplar/include/plat_private.h
index e2272cc..845b1bd 100644
--- a/plat/hisilicon/poplar/include/plat_private.h
+++ b/plat/hisilicon/poplar/include/plat_private.h
@@ -24,7 +24,6 @@
 			    unsigned long coh_start,
 			    unsigned long coh_limit);
 
-void plat_delay_timer_init(void);
 void plat_io_setup(void);
 
 #endif /* __PLAT_PRIVATE_H__ */