arc: Improve comments for gas:file_exists()

Signed-off-by: Anton Kolesov <Anton.Kolesov@synopsys.com>
arc: Refactor get_extension_lib_path()

Signed-off-by: Anton Kolesov <Anton.Kolesov@synopsys.com>
arc: Minor formatting change

Signed-off-by: Anton Kolesov <Anton.Kolesov@synopsys.com>
arc: Fix comment

Signed-off-by: Anton Kolesov <Anton.Kolesov@synopsys.com>
arc:" Fix typo

Signed-off-by: Anton Kolesov <Anton.Kolesov@synopsys.com>