drm/hisilicon: Remove drm_dev_put in hibmc

Hibmc use the devm_drm_dev_alloc function in hibmc_pci_probe, if
hibmc_pci_probe returns non-zero, devm_drm_dev_alloc will call
devm_drm_dev_init, which will call devm_drm_dev_init_release to
release drm_dev_put. There is no need for hibmc to call
drm_dev_put separately.

Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/1608638156-7879-1-git-send-email-tiantao6@hisilicon.com