HID: elan: Make array buf static, shrinks object size

Don't populate the array buf on the stack but instead make it
static. Makes the object code smaller by 43 bytes:

Before:
   text	   data	    bss	    dec	    hex	filename
   7769	   1520	      0	   9289	   2449	drivers/hid/hid-elan.o

After:
   text	   data	    bss	    dec	    hex	filename
   7662	   1584	      0	   9246	   241e	drivers/hid/hid-elan.o

(gcc version 8.2.0 x86_64)
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/hid-elan.c

@@ -393,7 +393,7 @@ static int elan_start_multitouch(struct hid_device *hdev)
 	 * This byte sequence will enable multitouch mode and disable
 	 * mouse emulation
 	 */
-	const unsigned char buf[] = { 0x0D, 0x00, 0x03, 0x21, 0x00 };
+	static const unsigned char buf[] = { 0x0D, 0x00, 0x03, 0x21, 0x00 };
 	unsigned char *dmabuf = kmemdup(buf, sizeof(buf), GFP_KERNEL);
 
 	if (!dmabuf)