Enable testing kernel.
Fix compile errors by using new kernel APIs.
Fix fuzz by manually editing patches to ensure the code goes in the
right place.
For 721-NET-no-auto-carrier-off-support.patch, revert upstream commit
a307593a6 to keep the OpenWrt ralink driver operational.
Add mt7621-pci-phy patch to select REGMAP_MMIO as discussed in PR #3693
and #3952.
Run automatic quilt refresh on the rest.
Signed-off-by: Ilya Lipnitskiy <ilya.lipnitskiy@gmail.com>