Remove disable_blurs sysprop from SF

The disable_blurs sysprop is now redundant, because the window-level
blurs are disabled in the system server. If blurs are supported on the
device, SurfaceFlinger should render them.

Bug: 185580298
Test: m && flash
Change-Id: If4503a26416d3586e85a14c9e3c0052173235e6f
2 files changed