DF-1251 fix build validation (incremental radeon.ko rebuild with the combios
loop-bound changes applied on top of the DF-1246+DF-1250 radeon tree):

Applied the radeon_combios.c portion of DF-1251's fix.diff (3 hunks,
mmio/pll/ram-reset loop bounds) on top of the already-built radeon module
tree (warm obj), then rebuilt:

  cd /usr/src/sys/dev/drm/radeon && make KERNCONF=X86_64_GENERIC KERNDIR=/usr/src/sys

patch output:
  Hunk #1 succeeded at 3019 (offset 12 lines).   (combios_parse_mmio_table)
  Hunk #2 succeeded at 3103 (offset 12 lines).   (combios_parse_pll_table)
  Hunk #3 succeeded at 3198 (offset 12 lines).   (combios_parse_ram_reset_table)

rebuild output (tail):
  cc ... -Werror -DKLD_MODULE ... -c radeon_combios.c
  ...
  === RADEON_REBUILD_DONE rc=0 ===

Conclusion: DF-1251's fix compiles cleanly into radeon.ko with -Werror.
(DF-1251 shares the bios_length infrastructure with DF-1250, whose full
radeon.ko build is in DF-1250/fix_build.log and also rc=0.)