exynos: Cleanup exynos_init

- None of the callers perform error checking and based on the non-empty
  versions of this function, there's no checking to be done, so make
  this a void.
- Add a default weak version of the function.
- Remove the empty versions of exynos_init now that we have a weak
  version.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/board/samsung/common/board.c b/board/samsung/common/board.c
index 663d7ca..5a71982 100644
--- a/board/samsung/common/board.c
+++ b/board/samsung/common/board.c
@@ -43,6 +43,10 @@
 	return 0;
 }
 
+__weak void exynos_init(void)
+{
+}
+
 __weak int exynos_power_init(void)
 {
 	return 0;
@@ -113,7 +117,9 @@
 	gd->ram_size -= size;
 	gd->bd->bi_dram[CONFIG_NR_DRAM_BANKS - 1].size -= size;
 #endif
-	return exynos_init();
+	exynos_init();
+
+	return 0;
 }
 
 int dram_init(void)