drm: Remove unused arg from drm_fb_helper_init

The max connector argument for drm_fb_helper_init() isn't used anymore
hence remove it.

All the drm_fb_helper_init() calls are modified with below sementic
patch.

@@
expression E1, E2, E3;
@@
-  drm_fb_helper_init(E1,E2, E3)
+  drm_fb_helper_init(E1,E2)

Signed-off-by: Pankaj Bharadiya <pankaj.laxminarayan.bharadiya@intel.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20200305120434.111091-2-pankaj.laxminarayan.bharadiya@intel.com