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/boot/Makefile b/arch/xtensa/boot/Makefile
index 70fd145..4018f89 100644
--- a/arch/xtensa/boot/Makefile
+++ b/arch/xtensa/boot/Makefile
@@ -25,7 +25,7 @@
 bootdir-$(CONFIG_XTENSA_PLATFORM_XT2000) += boot-redboot boot-elf
 
 
-zImage zImage.initrd Image Image.initrd: $(bootdir-y)
+zImage Image: $(bootdir-y)
 
 $(bootdir-y): $(addprefix $(obj)/,$(subdir-y)) \
 	      $(addprefix $(obj)/,$(host-progs))