cinergyT2, remove bad usage of ERESTARTSYS

test of cinergyt2->disconnect_pending doesn't ensure pending signal and so
ERESTARTSYS would reach userspace, which is not permitted. Change it to
EAGAIN.
Signed-off-by: NJiri Slaby <jirislaby@gmail.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@infradead.org>