The gain is two-fold:
- Removes the need of preprocessor conditionals in the timer drivers'
ISRs.
- Allows removing the duplication of the 'tick announce' code across
all timer drivers.
Change-Id: I6078a0b00a833c1d1ca76474987c3214a0c05f7b
Signed-off-by: Benjamin Walsh <benjamin.walsh@windriver.com>