haven: msgq: Initialize the cap-id with U64_MAX

Currently, the cap-id for Tx and Rx of the message-queue are
initialized with 0. However, 0 is a valid value for cap-id.
A better value to initialize the cap-id is with U64_MAX. Hence,
make corrections to use U64_MAX, defined as HH_CAPID_INVAL, in
the message-queue driver.

Change-Id: Ia501e87dc3cb8d880ea3d35ff000ca07b64aeced
Signed-off-by: Raghavendra Rao Ananta <rananta@codeaurora.org>