Convert CONFIG_BOARD_POSTCLK_INIT to Kconfig

This converts the following to Kconfig:
   CONFIG_BOARD_POSTCLK_INIT

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/common/Kconfig b/common/Kconfig
index 82cd864..add4cda 100644
--- a/common/Kconfig
+++ b/common/Kconfig
@@ -524,6 +524,12 @@
 	  relocation. With this option, U-Boot calls board_early_init_r()
 	  in the post-relocation init sequence.
 
+config BOARD_POSTCLK_INIT
+	bool "Call board_postclk_init"
+	help
+	  Some boards need this to initialize select items, after clocks /
+	  timebase and before env / serial.
+
 config BOARD_LATE_INIT
 	bool "Execute Board late init"
 	help