Remove duplicate BUILD.gn configuration

There's another `if (skia_llvm_path != "")` about 40 lines down.

Bug: skia:
Change-Id: I490c0972367d0042e5f87868c0640cc106f6f6c2
Reviewed-on: https://skia-review.googlesource.com/154260
Reviewed-by: Leon Scroggins <scroggo@google.com>
Commit-Queue: Leon Scroggins <scroggo@google.com>
1 file changed