ARM: Set CLK_EVT_FEAT_DYNIRQ flag memory mapped timers

Memory mapped timers are used as broadcast timers to wake up a core
across reset. CLK_EVT_FEAT_DYNIRQ ensures only the intended cores are
woken up instead of the default core that they are routed to, thereby
saving power.

Change-Id: I523b617fa32da5b27c390db5297b50d4743f4b34
Signed-off-by: Mahesh Sivasubramanian <msivasub@codeaurora.org>