serial: sunhv: Free memory when remove() is called

In each call to hv_remove(), con_read_page and con_write_page is not
getting freed and lead to memory leakage. Fix this by freeing both
pointers in hv_remove().

Signed-off-by: Souptick joarder <jrdr.linux@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>