am33xx: board: Call spl_early_init() to support sdram_init()

With driver model enabled in SPL, sdram_init() requires device tree
and malloc to be initialized.
Therefore call spl_early_init() in early_system_init().

Signed-off-by: Faiz Abbas <faiz_abbas@ti.com>
Reviewed-by: Lokesh Vutla <lokeshvutla@ti.com>

arch/arm/mach-omap2/am33xx/board.c

@@ -353,6 +353,9 @@ void early_system_init(void)
 #ifdef CONFIG_TI_I2C_BOARD_DETECT
 	do_board_detect();
 #endif
+#ifdef CONFIG_SPL_BUILD
+	spl_early_init();
+#endif
 #if defined(CONFIG_SPL_AM33XX_ENABLE_RTC32K_OSC)
 	/* Enable RTC32K clock */
 	rtc32k_enable();