openssl: remove call to now absent clean-staging make target

It's not needed now since commit a621b8c ("include: clean package
staging dir files before configure")

Fixes FS#1309

Signed-off-by: Yousong Zhou <yszhou4tech@gmail.com>

package/libs/openssl/Makefile

@@ -194,9 +194,6 @@ define Build/Configure
 			$(OPENSSL_NO_CIPHERS) \
 			$(OPENSSL_OPTIONS) \
 	)
-	# XXX: OpenSSL "make depend" will look for installed headers before its own,
-	# so remove installed stuff first
-	-$(SUBMAKE) -j1 clean-staging
 	+$(MAKE) $(PKG_JOBS) -C $(PKG_BUILD_DIR) \
 		CROSS_COMPILE="$(TARGET_CROSS)" \
 		MAKEDEPPROG="$(TARGET_CROSS)gcc" \