hwc: Fixup for L

Revert "display-legacy: clarify COPYBIT == HWC_BLIT"

This reverts commit b4331823c8c285cf757085fa265720703d52abc3.

Revert "hwc: dont mistake COPYBIT for FRAMEBUFFER_TARGET"

This reverts commit fd23a891779c8c938ac9cd0e7087a89145ac2ea3.

Change-Id: I5939aad2d3dfc03a928caf0b63cde6ba9cb9c935