Update to 6.8-rc7
    
    - eliminate 1 mainline patch
      - patches.rpmify/net-ethernet-adi-move-PHYLIB-from-vendor-to-driver-s.patch (943d4bd67950)
    - update riscv64 configs
      - RISCV_ISA_V=y
      - RISCV_ISA_V_DEFAULT_ENABLE=y
      - RISCV_ISA_V_UCOPY_THRESHOLD=768
      - RISCV_ISA_V_PREEMPTIVE=y
      - RISCV_ISA_ZBB=y