slimbus: Populate slimbus device's logical address during assignment

Slimbus device is assigned logical address when it reports present.
Make sure to populate the device's logical address (laddr) during
this assignment.

CRs-Fixed: 412148
Change-Id: Icb8d74f6ea71aff8f6cb30523002f7839e2cb028
Signed-off-by: Sagar Dharia <sdharia@codeaurora.org>