glsl: remove unnecessary parenthesis from macro

The "__inst" will contain the name used for the variable of type
"__type *". Parenthesis is not necessary as the name itself shouldn't
be an expression.

Fixes warning:

In file included from ../../src/mesa/main/mtypes.h:49,
                 from ../../src/intel/compiler/brw_compiler.h:30,
                 from ../../src/intel/compiler/brw_shader.h:29,
                 from ../../src/intel/compiler/brw_fs.h:31,
                 from ../../src/intel/compiler/brw_fs_cse.cpp:24:
../../src/intel/compiler/brw_fs_cse.cpp: In member function ‘bool fs_visitor::opt_cse_local(bblock_t*)’:
../../src/compiler/glsl/list.h:675:12: warning: unnecessary parentheses in declaration of ‘entry’ [-Wparentheses]
    __type *(__inst);                                      \
            ^
../../src/intel/compiler/brw_fs_cse.cpp:257:10: note: in expansion of macro ‘foreach_in_list_use_after’
          foreach_in_list_use_after(aeb_entry, entry, &aeb) {
          ^~~~~~~~~~~~~~~~~~~~~~~~~

Reviewed-by: Anuj Phogat <anuj.phogat@gmail.com>

src/compiler/glsl/list.h

@@ -672,7 +672,7 @@ inline void exec_node::insert_before(exec_list *before)
         __node = __prev, __prev = (__type *)__prev->prev)
 
 #define foreach_in_list_use_after(__type, __inst, __list) \
-   __type *(__inst);                                      \
+   __type *__inst;                                        \
    for ((__inst) = (__type *)(__list)->head_sentinel.next; \
         !(__inst)->is_tail_sentinel();                    \
         (__inst) = (__type *)(__inst)->next)