hh_rm_core: delay sending characters to RM

No flow control mechanism exist in RM console. That means when there is
huge messages sent from SVM to PVM there is a possibility that messages
being dropped by RM and hence loss of messages on console. Add a delay
of 800us for every console write and flush calls.

Change-Id: I65fb7a347b093d079c1380765c63b38bf90e0b66
Signed-off-by: Murali Nalajala <mnalajal@codeaurora.org>