USB: Fix a memory leak in em28xx_usb_probe()

If, in em28xx_usb_probe() the memory allocation
	dev->alt_max_pkt_size = kmalloc(32*
						dev->num_alt,GFP_KERNEL);
fails, then we'll bail out and return -ENOMEM.
The problem is that in that case we don't free the storage allocated
to 'dev', thus causing a memory leak.

This patch fixes the leak by freeing 'dev' before we return -ENOMEM.
This fixes Coverity bug #647.


Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>