Convert CONFIG_SPL_NOR_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/uniphier_pro4_defconfig b/configs/uniphier_pro4_defconfig
index a7dcc56..8ee2e84 100644
--- a/configs/uniphier_pro4_defconfig
+++ b/configs/uniphier_pro4_defconfig
@@ -3,6 +3,7 @@
 CONFIG_MICRO_SUPPORT_CARD=y
 CONFIG_SYS_TEXT_BASE=0x84000000
 CONFIG_DEFAULT_DEVICE_TREE="uniphier-ph1-pro4-ref"
+CONFIG_SPL_NOR_SUPPORT=y
 CONFIG_HUSH_PARSER=y
 CONFIG_CMD_BOOTZ=y
 # CONFIG_CMD_XIMG is not set