xtensa: drop CONFIG_EMBEDDED_RAMDISK

Remove Kconfig entries, boot subdirectory, dependencies from other
boot-* Makefiles, and sections from ld scripts.

Remove stale redboot code that used to pass initrd addresses in a3 and
a4 to _start.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>
diff --git a/arch/xtensa/Makefile b/arch/xtensa/Makefile
index b201d44..735916b 100644
--- a/arch/xtensa/Makefile
+++ b/arch/xtensa/Makefile
@@ -48,12 +48,6 @@
 
 KBUILD_DEFCONFIG := iss_defconfig
 
-# ramdisk/initrd support
-# You need a compressed ramdisk image, named ramdisk.gz in
-# arch/xtensa/boot/ramdisk
-
-core-$(CONFIG_EMBEDDED_RAMDISK)	+= arch/xtensa/boot/ramdisk/
-
 # Test for cross compiling
 
 ifneq ($(VARIANT),)
@@ -87,7 +81,7 @@
 
 bzImage : zImage
 
-zImage zImage.initrd: vmlinux
+zImage: vmlinux
 	$(Q)$(MAKE) $(build)=$(boot) $@
 
 define archhelp