mhi: core: add time synchronization feature support

Allows MHI client(s) to query current time for host and
device using direct api or using sysfs entry from userspace.

CRs-Fixed: 2332909
Change-Id: Ied2134433d8ea19c649a129021c5629a47f953bf
Acked-by: Bhaumik Vasav Bhatt <bbhatt@qti.qualcomm.com>
Signed-off-by: Sujeev Dias <sdias@codeaurora.org>