drm/vc4: Fix resource leak in 'vc4_get_hang_state_ioctl()' in error handling path

drm/vc4: Fix resource leak in 'vc4_get_hang_state_ioctl()' in error handling path

[ Upstream commit d0b1d259a4b58b21a21ea82d7174bf7ea825e9cc ]

If one 'drm_gem_handle_create()' fails, we leak somes handles and some
memory.

In order to fix it:
  - move the 'free(bo_state)' at the end of the function so that it is also
    called in the eror handling path. This has the side effect to also try
    to free it if the first 'kcalloc' fails. This is harmless.
  - add a new label, err_delete_handle, in order to delete already
    allocated handles in error handling path
  - remove the now useless 'err' label

The way the code is now written will also delete the handles if the
'copy_to_user()' call fails.

Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Eric Anholt <eric@anholt.net>
Link: http://patchwork.freedesktop.org/patch/msgid/20170512123803.1886-1-christophe.jaillet@wanadoo.fr
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>