Convert CONFIG_SPL_DRIVERS_MISC_SUPPORT to Kconfig

Move this option to Kconfig and tidy up existing uses.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/C29XPCIE_NAND_defconfig b/configs/C29XPCIE_NAND_defconfig
index 1c3f07d..fd1f9f3 100644
--- a/configs/C29XPCIE_NAND_defconfig
+++ b/configs/C29XPCIE_NAND_defconfig
@@ -9,6 +9,7 @@
 CONFIG_BOOTDELAY=-1
 CONFIG_SPL=y
 CONFIG_TPL=y
+CONFIG_SPL_DRIVERS_MISC_SUPPORT=y
 CONFIG_HUSH_PARSER=y
 CONFIG_CMD_SF=y
 CONFIG_CMD_I2C=y