Remove MIPS targets from CI LLVM platforms

All of these were demoted to tier 3 a while ago and we aren't building
LLVM for them anymore.

Signed-off-by: Jens Reidel <[email protected]>

Author: Gelbpunkt

src/bootstrap/src/core/build_steps/llvm.rs

@@ -220,10 +220,6 @@ pub(crate) fn is_ci_llvm_available_for_target(
         ("armv7-unknown-linux-gnueabihf", false),
         ("loongarch64-unknown-linux-gnu", false),
         ("loongarch64-unknown-linux-musl", false),
-        ("mips-unknown-linux-gnu", false),
-        ("mips64-unknown-linux-gnuabi64", false),
-        ("mips64el-unknown-linux-gnuabi64", false),
-        ("mipsel-unknown-linux-gnu", false),
         ("powerpc-unknown-linux-gnu", false),
         ("powerpc64-unknown-linux-gnu", false),
         ("powerpc64le-unknown-linux-gnu", false),