[AMD] Reland "Add gfx950 target definitions" (triton-lang#5392)

This relands triton-lang#5392
to enable new arch target since backend support has been
added--it doesn't depend on the reverted LLVM upgrade in
triton-lang#5341; basic
necessary enablement is already included in the current llvm
version we're using.

(cherry picked from commit f257479)

Author: jungpark-mlir

third_party/amd/backend/include/hsa/amd_hsa_elf.h

@@ -130,6 +130,7 @@ enum : unsigned {
   EF_AMDGPU_MACH_AMDGCN_GFX1151       = 0x04a,
   EF_AMDGPU_MACH_AMDGCN_GFX941        = 0x04b,
   EF_AMDGPU_MACH_AMDGCN_GFX942        = 0x04c,
+  EF_AMDGPU_MACH_AMDGCN_GFX950        = 0x04f,
 
   // First/last AMDGCN-based processors.
   EF_AMDGPU_MACH_AMDGCN_FIRST = EF_AMDGPU_MACH_AMDGCN_GFX600,

third_party/amd/lib/TritonAMDGPUToLLVM/TargetUtils.cpp

@@ -11,6 +11,7 @@ ISAFamily deduceISAFamily(llvm::StringRef arch) {
 
   // CDNA ISA cases
   switch (kind) {
+  case llvm::AMDGPU::GK_GFX950:
   case llvm::AMDGPU::GK_GFX942:
   case llvm::AMDGPU::GK_GFX941:
   case llvm::AMDGPU::GK_GFX940: