Rollup merge of #120495 - clubby789:remove-amdgpu-kernel, r=oli-obk

Remove the `abi_amdgpu_kernel` feature

The tracking issue (#51575) has been closed for 3 years, with no activity for 5.

compiler/rustc_target/src/spec/mod.rs

@@ -2457,7 +2457,6 @@ impl Target {
             Win64 { .. } | SysV64 { .. } => self.arch == "x86_64",
             PtxKernel => self.arch == "nvptx64",
             Msp430Interrupt => self.arch == "msp430",
-            AmdGpuKernel => self.arch == "amdgcn",
             RiscvInterruptM | RiscvInterruptS => ["riscv32", "riscv64"].contains(&&self.arch[..]),
             AvrInterrupt | AvrNonBlockingInterrupt => self.arch == "avr",
             Wasm => ["wasm32", "wasm64"].contains(&&self.arch[..]),