bunch of coverity fixes all minor.
* 'drm-coverity-fixes' of git://people.freedesktop.org/~danvet/drm:
drm: Fix error handling in drm_master_create
drm/i2c/tda998x: Fix signed overflow issue
drm/bochs: Remove unecessary NULL check in gem_free
drm/bochs: Remove unnecessary NULL check in bo_unref
drm/udl: Initialize ret in udl_driver_load
drm/via: Remove unecessary NULL check
drm/ast: Remove unecessary NULL check in gem_free
drm/ast: Remove unnecessary NULL check in bo_unref
drm/cirrus: Remove unecessary NULL check in gem_free
drm/cirrus: Remove unnecessary NULL check in bo_unref
drm/mgag200: Remove unecessary NULL check in gem_free
drm/mgag200: Remove unecessary NULL check in bo_unref