[][openwrt][common][Fix build error in openssl-fips-ext]

[Description]
Remove Build/Prepare in Makefile.
Make it use default Build/Prepare.

[Release-log]

Change-Id: I5cfa60558c0f9e06779047776f17b4e74b45a5b5
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/8267477
diff --git a/feed/openssl-fips-ext/Makefile b/feed/openssl-fips-ext/Makefile
index 8a5b558..87dd9bb 100644
--- a/feed/openssl-fips-ext/Makefile
+++ b/feed/openssl-fips-ext/Makefile
@@ -25,14 +25,8 @@
 	Simple tool for gcm and ccm
 endef
 
-define Build/Prepare
-	mkdir -p $(PKG_BUILD_DIR)
-	mkdir -p $(PKG_BUILD_DIR)/src
-	$(CP) ./src/* $(PKG_BUILD_DIR)/src
-endef
-
 define Build/Compile
-	make -C ./src \
+	make -C $(PKG_BUILD_DIR) \
 		CC="$(TARGET_CC)" \
 		OPENSSL_INCS_LOCATION=-I$(STAGING_DIR)/usr/include/openssl \
 		OPENSSL_LIBS_LOCATION=-L$(STAGING_DIR)/usr/lib
@@ -40,8 +34,7 @@
 
 define Package/openssl-fips-ext/install
 	$(INSTALL_DIR) $(1)/bin
-	$(INSTALL_BIN) $(PKG_BUILD_DIR)/src/openssl-fips-ext $(1)/bin/
+	$(INSTALL_BIN) $(PKG_BUILD_DIR)/openssl-fips-ext $(1)/bin/
 endef
 
 $(eval $(call BuildPackage,openssl-fips-ext))
-
diff --git a/feed/openssl-fips-ext/src/Makefile b/feed/openssl-fips-ext/src/Makefile
index 4d8282e..28e8bab 100644
--- a/feed/openssl-fips-ext/src/Makefile
+++ b/feed/openssl-fips-ext/src/Makefile
@@ -18,4 +18,4 @@
 	$(CC) $(CFLAGS) -c -o common.o $< $(LDFLAGS)
 
 clean:
-	$(RM) openssl-fips-ext
+	$(RM) openssl-fips-ext *.o