r600g: emit NOPs at end of shaders in more cases

r600g: emit NOPs at end of shaders in more cases

If the shader has no CF clauses at all emit an nop
If the last instruction is an ENDLOOP add a NOP for the LOOP to go to
if the last instruction is CALL_FS add a NOP

These fix a bunch of hangs in the geometry shader tests.

Signed-off-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>