tools: add intel_gpu_frequency to .gitignore
tools: add intel_gpu_frequency to .gitignore

intel_gpu_frequency was added in commit 5fb26d1 (intel_gpu_frequency: A
tool to manipulate Intel GPU frequency), but wasn't added to .gitignore.

Cc: Ben Widawsky <cf148a1c890adeeb4308e9e093ed95f3d05c8318@intel.com>
Signed-off-by: Thomas Wood <b9025d6a953b68f894a0f6a80fd2af6d55b0badd@intel.com>

erikarn/intel-gpu-tools,mv0/intel-gpu-tools,chenxianqin/intel-gpu-tools,dlespiau/checkmate-test-igt,erikarn/intel-gpu-tools,chenxianqin/intel-gpu-tools,dlespiau/checkmate-test-igt,tiagovignatti/intel-gpu-tools,yipdw/intel-gpu-tools,chenxianqin/intel-gpu-tools,erikarn/intel-gpu-tools,tiagovignatti/intel-gpu-tools,mv0/intel-gpu-tools,yipdw/intel-gpu-tools,yipdw/intel-gpu-tools,dlespiau/checkmate-test-igt,tiagovignatti/intel-gpu-tools,dlespiau/checkmate-test-igt,yipdw/intel-gpu-tools,mv0/intel-gpu-tools,erikarn/intel-gpu-tools,mv0/intel-gpu-tools,chenxianqin/intel-gpu-tools,tiagovignatti/intel-gpu-tools