drm/etnaviv: Drop the <linux/pm_runtime.h> header

Currently, the etnaviv_gem_submit.c isn't call any runtime power management
functions. So drop this unused header, we can include it back when it
really get used though.

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

drivers/gpu/drm/etnaviv/etnaviv_gem_submit.c

···
 #include <drm/drm_file.h>
 #include <linux/dma-fence-array.h>
 #include <linux/file.h>
-#include <linux/pm_runtime.h>
 #include <linux/dma-resv.h>
 #include <linux/sync_file.h>
 #include <linux/uaccess.h>