ISDN, hfcsusb: Don't leak in hfcsusb_ph_info()

We leak the memory allocated to 'phi' when the variable goes out of scope
in hfcsusb_ph_info().

Signed-off-by: Jesper Juhl <jj@chaosbits.net>
Signed-off-by: David S. Miller <davem@davemloft.net>