intel/compiler: Fix brw_gfx_ver_enum.h to be a proper header file

This header file didn't include normal guards against being included
multiple times.  It also defined a function in a header file without
marking it static inline.

Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/17309>

src/intel/compiler/brw_gfx_ver_enum.h

@@ -21,6 +21,9 @@
  * IN THE SOFTWARE.
  */
 
+#ifndef BRW_GFX_VER_ENUM_H
+#define BRW_GFX_VER_ENUM_H
+
 #include "util/macros.h"
 #include "dev/intel_device_info.h"
 
@@ -44,7 +47,7 @@ enum gfx_ver {
 #define GFX_GE(ver) (~GFX_LT(ver))
 #define GFX_LE(ver) (GFX_LT(ver) | (ver))
 
-static enum gfx_ver
+static inline enum gfx_ver
 gfx_ver_from_devinfo(const struct intel_device_info *devinfo)
 {
    switch (devinfo->verx10) {
@@ -63,3 +66,5 @@ gfx_ver_from_devinfo(const struct intel_device_info *devinfo)
       unreachable("not reached");
    }
 }
+
+#endif