drm/malidp: Don't call drm_crtc_vblank_off on unbind

This is already done as part of the drm_atomic_helper_shutdown(),
and in that case only for the crtc which are actually on.

v2: I overlooked that malidp also needs to have it's interrupt shut
down reordered.

Acked-by: Liviu Dudau <liviu.dudau@arm.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Liviu Dudau <liviu.dudau@arm.com>
Cc: Brian Starkey <brian.starkey@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200602095505.37509-1-daniel.vetter@ffwll.ch