ARM: SPL: Move gpmc_init() to spl_board_init()

This is an OMAP/related-specific function, move calling it to
spl_board_init() and turn on CONFIG_SPL_BOARD_INIT on the boards that
enabled NAND and didn't enable this already.

Signed-off-by: Tom Rini <trini@ti.com>
diff --git a/include/configs/tam3517-common.h b/include/configs/tam3517-common.h
index a13fd93..b34cb78 100644
--- a/include/configs/tam3517-common.h
+++ b/include/configs/tam3517-common.h
@@ -239,6 +239,7 @@
 
 /* Defines for SPL */
 #define CONFIG_SPL
+#define CONFIG_SPL_BOARD_INIT
 #define CONFIG_SPL_CONSOLE
 #define CONFIG_SPL_NAND_SIMPLE
 #define CONFIG_SPL_NAND_SOFTECC