staging: rtl8192u: Fix some error handling path

If 'rtl8192_usb_initendpoints()' fails, it may have allocated some
resources that need to be freed. The corresponding is propagated up to
'rtl8192_usb_prob()'. So, in this function if an error
code is returned by 'rtl8192_init()' we should call
'rtl8192_usb_deleteendpoints()'.

Some error handling code is also duplicated in 'rtl8192_init()' and in
'rtl8192_usb_prob()'. This looks harmless because the freed pointers are
set to NULL but it looks confusing.

Fix all that by just moving the 'fail' label and removing duplicated
error handling code from 'rtl8192_ini()'. All this resources freeing will
be handled by 'rtl8192_usb_prob()' directly.

The calling graph is:
rtl8192_usb_probe
  --> rtl8192_init
    --> rtl8192_usb_initendpoints

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>