Remove redundant YYLOC global declaration
Cherry picked from https://github.com/u-boot/u-boot/commit/018921ee79d3f30893614b3b2b63b588d8544f73 to fix building with GCC 10
Cherry picked from https://github.com/u-boot/u-boot/commit/018921ee79d3f30893614b3b2b63b588d8544f73 to fix building with GCC 10