drm/etnaviv: flush shader L1 cache after user commandstream

The shader L1 cache is a writeback cache for shader loads/stores
and thus must be flushed before any BOs backing the shader buffers
are potentially freed.

Cc: [e-mail]
Reviewed-by: Christian Gmeiner <[e-mail]>
Signed-off-by: Lucas Stach <[e-mail]>

drivers/gpu/drm/etnaviv/etnaviv_buffer.c

···
 	} else {
 		CMD_LOAD_STATE(buffer, VIVS_GL_FLUSH_CACHE,
 				       VIVS_GL_FLUSH_CACHE_DEPTH |
-				       VIVS_GL_FLUSH_CACHE_COLOR);
+				       VIVS_GL_FLUSH_CACHE_COLOR |
+				       VIVS_GL_FLUSH_CACHE_SHADER_L1);
 		if (has_blt) {
 			CMD_LOAD_STATE(buffer, VIVS_BLT_ENABLE, 0x1);
 			CMD_LOAD_STATE(buffer, VIVS_BLT_SET_COMMAND, 0x1);