staging: greybus: Remove redundant 'flush_workqueue()' calls

'destroy_workqueue()' already drains the queue before destroying it,
so there is no need to flush it explicitly.

Remove the redundant 'flush_workqueue()' calls.

Reported-by: Zeal Robot <[e-mail]>
Reviewed-by: Rui Miguel Silva <[e-mail]>
Signed-off-by: Minghao Chi (CGEL ZTE) <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/staging/greybus/sdio.c

···
 	gb_connection_set_data(connection, NULL);
 	mutex_unlock(&host->lock);
 
-	flush_workqueue(host->mrq_workqueue);
 	destroy_workqueue(host->mrq_workqueue);
 	gb_connection_disable_rx(connection);
 	mmc_remove_host(mmc);