[MLIR] Fix triple mismatch warning for embedded libdevice (#121447)
IRLinker emits warning when linking two modules of different target
triples. The warning is disabled if the source module is libdevice. When
using libdevice embedded in LLVM library via MLIR_NVVM_EMBED_LIBDEVICE,
IRLinker can no longer tell whether the source module is libdevice via
module identifier.
Since `nvptx64-nvidia-gpulibs` is a magic triple that identifies the
libdevice module already, the libdevice filename check is redundant.
This patch fixes the triple mismatch warning by just removing the
filename check.