Regular update of Leap 15.0 kernel

- Really drop the disabled DRM patches
Some DRM patches have been disabled due to regressions, and they have no
chance for revive on SLE15-SP0, at least. So better to drop them for
avoiding confusion. No code change in the expanded tree by this.
- commit fd2445a

- Btrfs: send, fix infinite loop due to directory rename
dependencies (bsc#1118138).
- commit 3add617

- Delete patches.drm/drm-dp_mst-Skip-validating-ports-during-destruction-.patch (bsc#1051510)
The commit was reverted in the upstream. Put both in the blacklist now.
- commit 9ee57e7

- Refresh
patches.fixes/dax-remove-VM_MIXEDMAP-for-fsdax-and-device-dax.patch.
Fixed missing hunk (bsc#1118102).
- commit 478866a

- net/ibmvnic: Fix RTNL deadlock during device reset
(bnc#1115431).
- commit 87ebdb1

- Btrfs: fix cur_offset in the error case for nocow (bsc#1118140).
- commit 3a69a03

- Btrfs: fix assertion on fsync of regular file when using
no-holes feature (bsc#1118137).
- commit 823bf85