morello: fix timestamp in debug logs

The generic timer instance is not hooked to the framework time driver
which makes the timestamp to be printed as zeros all the time.

This patch fixes the gap to let framework print correct timestamps
during debug logs.

Signed-off-by: Manoj Kumar <manoj.kumar3@arm.com>
Change-Id: Iacab58a01999be8f71358d13e48c1517dba02b64