Floss: Make inquiry length configurable in sysprop

For some chipset, we observed that it has lower performance in the
default inquiry parameters. This change allows Floss to configure
different parameters in different boards.

Bug: 320223219
Test: manually update /var/lib/bluetooth/sysprop.conf and verify the
inquiry length is changed accordingly
Tag: #floss
Test: mma -j
Flag: EXEMPT floss only changes

Change-Id: I5b98970812512a82439e8998ff25169c24c6096c