drm/i915: Replace empty conditional with continue in eb_relocate_vma()

Simplifies the control flow by replacing an empty
`if (likely(offset == 0))` block with a `continue` statement. This
improves readability and avoids unnecessary nesting.

Signed-off-by: Sebastian Brzezinka <sebastian.brzezinka@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://lore.kernel.org/r/20250718102752.684975-4-sebastian.brzezinka@intel.com