The devm_memremap() function doesn't return NULL, it returns error
pointers.
Fixes: 9a10c7e6519b ("drm/simpledrm: Add support for system memory framebuffers") Signed-off-by: Dan Carpenter <error27@gmail.com> Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de> Signed-off-by: Thierry Reding <treding@nvidia.com> Link: https://patchwork.freedesktop.org/patch/msgid/Y9JHzImRcUaa0mi1@kili
(cherry picked from commit e566507bf2f460967f53030ef84b67ef26dcaf8e) Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>