includes: move openssl headers to include/u-boot

commit 18b06652cd "tools: include u-boot version of sha256.h"
unconditionally forced the sha256.h from u-boot to be used
for tools instead of the host version. This is fragile though
as it will also include the host version. Therefore move it
to include/u-boot to join u-boot/md5.h etc which were renamed
for the same reason.

cc: Simon Glass <sjg@chromium.org>
Signed-off-by: Jeroen Hofstee <jeroen@myspectrum.nl>

tools/Makefile

@@ -192,7 +192,6 @@ endif # !LOGO_BMP
 # Define _GNU_SOURCE to obtain the getline prototype from stdio.h
 #
 HOST_EXTRACFLAGS += -include $(srctree)/include/libfdt_env.h \
-		-include $(srctree)/include/sha256.h \
 		$(patsubst -I%,-idirafter%, $(UBOOTINCLUDE)) \
 		-I$(srctree)/lib/libfdt \
 		-I$(srctree)/tools \