iperf: fix PKG_CONFIG_DEPENDS

Fix typo in PKG_CONFIG_DEPENDS and missing CONFIG_ prefix.

Fixes: e98e046f06 ("iperf: Allow enabling multicast support")
Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>

package/network/utils/iperf/Makefile

@@ -20,7 +20,7 @@ PKG_LICENSE:=BSD-3-Clause
 
 PKG_BUILD_PARALLEL:=1
 
-PGK_CONFIG_DEPENDS:=IPERF_ENABLE_MULTICAST
+PKG_CONFIG_DEPENDS:=CONFIG_IPERF_ENABLE_MULTICAST
 
 include $(INCLUDE_DIR)/uclibc++.mk
 include $(INCLUDE_DIR)/package.mk