package/busybox: fix target-finalize hook

It was searching for CONFIG_ASH=y and CONFIG_HUSH=y at $(@D)/.config,
which does not contain the package build path at the target-finalize
step. Use $(BUSYBOX_DIR), instead.

Signed-off-by: Carlos Santos <unixmania@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit 9ab1d565eef8935694d12bff2cd33c64b7a97f0f)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/busybox/busybox.mk

@@ -318,11 +318,11 @@ endef
 # Add /bin/{a,hu}sh to /etc/shells otherwise some login tools like dropbear
 # can reject the user connection. See man shells.
 define BUSYBOX_INSTALL_ADD_TO_SHELLS
-	if grep -q CONFIG_ASH=y $(@D)/.config; then \
+	if grep -q CONFIG_ASH=y $(BUSYBOX_DIR)/.config; then \
 		grep -qsE '^/bin/ash$$' $(TARGET_DIR)/etc/shells \
 		|| echo "/bin/ash" >> $(TARGET_DIR)/etc/shells; \
 	fi
-	if grep -q CONFIG_HUSH=y $(@D)/.config; then \
+	if grep -q CONFIG_HUSH=y $(BUSYBOX_DIR)/.config; then \
 		grep -qsE '^/bin/hush$$' $(TARGET_DIR)/etc/shells \
 		|| echo "/bin/hush" >> $(TARGET_DIR)/etc/shells; \
 	fi