Add #include <linux/slab.h> to avoid compilation errors

With the new versions of kernel, it is mandatory to include
the <linux/slab.h> file, if one uses kzalloc and kfree functions.

Signed-off-by: Sankar P <[email protected]>

Author: psankar

src/step-3/gotemp.c

@@ -2,6 +2,7 @@
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/usb.h>
+#include <linux/slab.h>
 
 #define VENDOR_ID	0x08f7
 #define PRODUCT_ID	0x0002

src/step-4/gotemp.c

@@ -2,6 +2,7 @@
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/usb.h>
+#include <linux/slab.h>
 
 #define VENDOR_ID	0x08f7
 #define PRODUCT_ID	0x0002

src/step-5/gotemp.c

@@ -2,6 +2,7 @@
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/usb.h>
+#include <linux/slab.h>
 
 #define VENDOR_ID	0x08f7
 #define PRODUCT_ID	0x0002

src/step-6/gotemp.c

@@ -2,6 +2,7 @@
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/usb.h>
+#include <linux/slab.h>
 
 #define VENDOR_ID	0x08f7
 #define PRODUCT_ID	0x0002