mmc-utils: fix typo in Makefile

Signed-off-by: Michael Heimpold <mhei@heimpold.de>

utils/mmc-utils/Makefile

@@ -14,7 +14,7 @@ PKG_RELEASE:=1
 PKG_SOURCE_PROTO:=git
 PKG_SOURCE_URL:=https://git.kernel.org/pub/scm/linux/kernel/git/cjb/mmc-utils.git
 PKG_SOURCE_VERSION:=f4eb241519f8d500ce6068a70d2389be39ac5189
-PKG_SOURCE_SUBDIR:=$(PKG_NAME)-$(PKG_VERSION)
+PKG_SOURCE_SUBDIR:=$(PKG_NAME)-$(PKG_SOURCE_VERSION)
 PKG_SOURCE:=$(PKG_NAME)-$(PKG_SOURCE_VERSION).tar.gz
 
 PKG_LICENSE:=GPL-2.0