plugins: Use emit_before_op for PLUGIN_GEN_FROM_TB

By having the qemu_plugin_cb_flags be recorded in the TCGHelperInfo,
we no longer need to distinguish PLUGIN_CB_REGULAR from
PLUGIN_CB_REGULAR_R, so place all TB callbacks in the same queue.

Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

plugins/api.c

@@ -92,11 +92,7 @@ void qemu_plugin_register_vcpu_tb_exec_cb(struct qemu_plugin_tb *tb,
                                           void *udata)
 {
     if (!tb->mem_only) {
-        int index = flags == QEMU_PLUGIN_CB_R_REGS ||
-                    flags == QEMU_PLUGIN_CB_RW_REGS ?
-                    PLUGIN_CB_REGULAR_R : PLUGIN_CB_REGULAR;
-
-        plugin_register_dyn_cb__udata(&tb->cbs[index],
+        plugin_register_dyn_cb__udata(&tb->cbs[PLUGIN_CB_REGULAR],
                                       cb, flags, udata);
     }
 }