firmware: ti_sci: Fix TISCI mailbox receive timeout handling

firmware: ti_sci: Fix TISCI mailbox receive timeout handling

An earlier commit converted the TISCI receive timeouts to be specified
in ms rather than us however it failed to take this change into account
when passing the actual timeout to be used when invoking the mailbox
receive API. This leads to the actual timeout to be 1,000 times shorter
than expected and as a result certain TISCI operations would fail.

Fix the issue by converting the timeout declared in ms to us on the fly
as expected by the respective API.

Fixes: 920cea07e0c5 ("firmware: ti_sci: Add support for NAVSS resource management")
Signed-off-by: Andreas Dannenberg <dannenberg@ti.com>
Reviewed-by: Lokesh Vutla <lokeshvutla@ti.com>