treewide: Remove OF_PRIOR_STAGE

The previous patches removed OF_PRIOR_STAGE from the last consumers of the
Kconfig option.  Cleanup any references to it in documentation,  code and
configuration options.

Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/dts/Kconfig b/dts/Kconfig
index 7a297b2..fc41305 100644
--- a/dts/Kconfig
+++ b/dts/Kconfig
@@ -22,7 +22,7 @@
 config BINMAN_STANDALONE_FDT
 	bool
 	depends on BINMAN
-	default y if OF_BOARD || OF_PRIOR_STAGE
+	default y if OF_BOARD
 	help
 	  This option tells U-Boot build system that a standalone device tree
 	  source is explicitly required when using binman to package U-Boot.
@@ -32,7 +32,7 @@
 	  directory for a specific board. Such device tree sources are built for
 	  OF_SEPARATE or OF_EMBED. However for a scenario like the board device
 	  tree blob is not provided in the U-Boot build tree, but fed to U-Boot
-	  in the runtime, e.g.: in the OF_PRIOR_STAGE case that it is passed by
+	  in the runtime, e.g.: in the OF_BOARD case that it is passed by
 	  a prior stage bootloader. For such scenario, a standalone device tree
 	  blob containing binman node to describe how to package U-Boot should
 	  be provided explicitly.
@@ -133,13 +133,6 @@
 	  This is only useful for Sandbox.  Use the -d flag to U-Boot to
 	  specify the file to read.
 
-config OF_PRIOR_STAGE
-	bool "Prior stage bootloader DTB for DT control"
-	help
-	  If this option is enabled, the device tree used for DT
-	  control will be read from a device tree binary, at a memory
-	  location passed to U-Boot by the prior stage bootloader.
-
 endchoice
 
 config DEFAULT_DEVICE_TREE