Convert CONFIG_BOARD_EARLY_INIT_F to Kconfig

This converts the following to Kconfig:
   CONFIG_BOARD_EARLY_INIT_F

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/sbc8548_PCI_33_PCIE_defconfig b/configs/sbc8548_PCI_33_PCIE_defconfig
index 3af5c70..56b9127 100644
--- a/configs/sbc8548_PCI_33_PCIE_defconfig
+++ b/configs/sbc8548_PCI_33_PCIE_defconfig
@@ -7,6 +7,7 @@
 CONFIG_SYS_EXTRA_OPTIONS="33,PCIE"
 CONFIG_BOOTDELAY=10
 # CONFIG_DISPLAY_BOARDINFO is not set
+CONFIG_BOARD_EARLY_INIT_F=y
 CONFIG_HUSH_PARSER=y
 CONFIG_CMD_I2C=y
 # CONFIG_CMD_SETEXPR is not set