Convert CONFIG_SYS_I2C_INIT_BOARD to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_I2C_INIT_BOARD

Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/board/keymile/Kconfig b/board/keymile/Kconfig
index 9f78443..b8f0578 100644
--- a/board/keymile/Kconfig
+++ b/board/keymile/Kconfig
@@ -11,6 +11,9 @@
 
 menu "KM Board Setup"
 
+config SYS_I2C_INIT_BOARD
+	def_bool y if ARM
+
 config HUSH_INIT_VAR
 	def_bool y