HWC2On1Adapter: Fix fd leak in Layer::dump

Removes the fence dump from Layer::dump, since:
  a) It was leaking (a dup() without a close())
  b) It's not that useful anyway since it wasn't displaying the actual
     fence fd

Test: Manual
Bug: 73979009
Change-Id: I8f7446a05a1bab8c3ca781610ebeb98d17fa483b