Floss: Log time spent in closing socket

We've recently observed that closing an HCI socket sometimes takes
longer than 1 second. This patch allows us to record the time it takes
to close the socket to further collect the high delay case by feedback
report analyzers.

Bug: 365936141
Tag: #floss
Test: mmm packages/modules/Bluetooth
Test: manual adaper enable/disable, verify the syslog
Flag: EXEMPT, Floss-only changes
Change-Id: I905358ad96b2eba244bf6ee26fa9059704396f31