drm/msm/mdp5: fixup "drm/msm: fix fallout of atomic dpms changes"

Commit 0b776d457b94 ("drm/msm: fix fallout of atomic dpms
changes") has a typo in both mdp5_encoder_helper_funcs and
mdp5_crtc_helper_funcs definitions:

	.dpms entry should be replaced by .disable and .enable

Also fixed a typo in mdp5_encoder_enable().

Note that these typos are only present for MDP5. MDP4 is fine.

Signed-off-by: Stephane Viau <sviau@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>