replace _mesa_logbase2 with util_logbase2

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Reviewed-by: Kristian H. Kristensen <hoegsberg@google.com>
Reviewed-by: Matt Turner <mattst88@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/3024>

src/intel/compiler/brw_ir_fs.h

@@ -298,8 +298,8 @@ subscript(fs_reg reg, brw_reg_type type, unsigned i)
       /* The stride is encoded inconsistently for fixed GRF and ARF registers
        * as the log2 of the actual vertical and horizontal strides.
        */
-      const int delta = _mesa_logbase2(type_sz(reg.type)) -
-                        _mesa_logbase2(type_sz(type));
+      const int delta = util_logbase2(type_sz(reg.type)) -
+                        util_logbase2(type_sz(type));
       reg.hstride += (reg.hstride ? delta : 0);
       reg.vstride += (reg.vstride ? delta : 0);