[PATCH v2] arch: arc: uapi: be sure of "_UAPI" prefix for all guard macros

For all uapi headers, need use "_UAPI" prefix for its guard macro (which will be stripped by "scripts/headers_installer.sh"). And be sure that all "endif" need append (or have correct) related comment, and all normal uapi header files need content guard macro. Also reserve guard macro in empty

[PATCH v2] arch: arc: uapi: be sure of _UAPI prefix for all guard macros

For all uapi headers, need use _UAPI prefix for its guard macro (which will be stripped by scripts/headers_installer.sh). And be sure that all endif need append (or have correct) related comment, and all normal uapi header files need content guard macro. Also reserve guard macro in empty file,