mtd: denali: 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.

Signed-off-by: Michal Marek <mmarek@suse.cz>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>