apq8084: Put MMC to sleep before starting kernel

Change mmc to sleep state prior to start of the Linux
kernel.  This ensures a consistent mmc controller
state for kernel bootup.

Change-Id: If9f057aa6772df5eea34ece3014c9ce29c667b6a
diff --git a/target/apq8084/init.c b/target/apq8084/init.c
index 3aaa70f..631edcb 100644
--- a/target/apq8084/init.c
+++ b/target/apq8084/init.c
@@ -116,6 +116,11 @@
 		keys_post_event(KEY_VOLUMEUP, 1);
 }
 
+void target_uninit(void)
+{
+	mmc_put_card_to_sleep(dev);
+}
+
 /* Do target specific usb initialization */
 void target_usb_init(void)
 {