hamradio: Remove unneeded and deprecated cli()/sti() calls in dmascc.c

These cli()/sti() calls are made in start_timer() and are therefor
redundant since the register_lock is now used to protect register
io from within scc_isr() and write_scc() (where all calls to
start_timer() originate).

Signed-off-by: Mark Asselstine <mark.asselstine@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>