hdlcdrv: Drop __TIME__ usage

The kernel already prints its build timestamp during boot, no need to
repeat it in random drivers and produce different object files each
time.

Acked-by: Thomas Sailer <t.sailer@alumni.ethz.ch>
Cc: linux-hams@vger.kernel.org
Cc: netdev@vger.kernel.org
Signed-off-by: Michal Marek <mmarek@suse.cz>