openfimg: Remove some unused remnants from freedreno driver

Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com>
openfimg: Reference vertex state object used by draw cache entry template

Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com>
openfimg: Simplify and extend scissor range checking

Negative ranges are invalid too.

Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com>
openfimg: Remove stale comment from of_emit_draw()

Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com>
openfimg: Remove redundant assignment in of_emit_draw()

Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com>