gf_w4.c: remove some dead code

Fix for coverity issue from Ceph project:

CID 1193093 (#1 of 1): Structurally dead code (UNREACHABLE)
 unreachable: This code cannot be reached: "return gf_w4_double_table_i...".

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>

src/gf_w4.c

@@ -793,7 +793,6 @@ int gf_w4_table_init(gf_t *gf)
     } else {
       return gf_w4_quad_table_init(gf);
     }
-    return gf_w4_double_table_init(gf);
   } else {
     return gf_w4_single_table_init(gf);
   }