iostat: remove legacy code

Some custom iostat-source target was mistakenly left in place when the
iostat package was migrated to gentargets in commit
ee77963588b09babfd71befb0b5eb9fd1e776bbc, back 4 years ago. This
commit removes this unnecessary custom target.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/iostat/iostat.mk

@@ -9,8 +9,6 @@ IOSTAT_SITE = http://www.linuxinsight.com/files
 IOSTAT_LICENSE = GPL
 IOSTAT_LICENSE_FILES = LICENSE
 
-iostat-source: $(DL_DIR)/$(IOSTAT_SOURCE)
-
 define IOSTAT_BUILD_CMDS
 	$(MAKE) -C $(@D) $(TARGET_CONFIGURE_OPTS)
 endef