hikey: update ddr initialization

Fix that DDR can't work at 533MHz. Now step to set DDR frequency
from 150MHz to 800MHz. DDR could work among these frequency, 150MHz,
266MHz, 400MHz, 533MHz and 800MHz.
Signed-off-by: Haojian Zhuang <haojian.zhuang@linaro.org>

plat/hisilicon/hikey/hikey_bl2_setup.c

@@ -306,7 +306,7 @@ void bl2_platform_setup(void)
 	hikey_hi6553_init();
 
 	dsb();
-	hikey_ddr_init();
+	hikey_ddr_init(DDR_FREQ_800M);
 	hikey_security_setup();
 
 	/* Clear SRAM since it'll be used by MCU right now. */

plat/hisilicon/hikey/hikey_private.h

@@ -12,6 +12,14 @@
 #define RANDOM_MAX		0x7fffffffffffffff
 #define RANDOM_MAGIC		0x9a4dbeaf
 
+enum {
+	DDR_FREQ_150M = 150 * 1000,
+	DDR_FREQ_266M = 266 * 1000,
+	DDR_FREQ_400M = 400 * 1000,
+	DDR_FREQ_533M = 533 * 1000,
+	DDR_FREQ_800M = 800 * 1000
+};
+
 struct random_serial_num {
 	uint64_t	magic;
 	uint64_t	data;
@@ -34,7 +42,7 @@ void hikey_init_mmu_el3(unsigned long total_base,
 			unsigned long coh_start,
 			unsigned long coh_limit);
 
-void hikey_ddr_init(void);
+void hikey_ddr_init(unsigned int ddr_freq);
 void hikey_io_setup(void);
 
 void hikey_sp804_init(void);