headers: drm: Sync with drm-next

Hello!
Running sway+wlroots with UBSan triggered the error (an undefined left shift) reported in !11 (closed). As noticed in the MR, the bug was fixed in Linux 5.5. I’ve followed the instructions and merged two headers, drm_fourcc.h and drm_mode.h (drm.h was up to date) from the latest commit in drm-next.
Please let me know if I need to change anything.

Generated using make headers_install from the drm-next
tree - git://anongit.freedesktop.org/drm/drm
branch - drm-next
commit - b10733527bfd864605c33ab2e9a886eec317ec39