!5564 serial: rp2: use 'request_firmware' instead of 'request_firmware_nowait'

Merge Pull Request from: @ci-robot 
 
PR sync from: Cai Xinchen <caixinchen1@huawei.com>
https://mailweb.openeuler.org/hyperkitty/list/kernel@openeuler.org/message/CBIY7ELVDRC2ILP7PXA7LRYUG5FX5O36/ 
 
https://gitee.com/src-openeuler/kernel/issues/I9BHLP 
 
Link:https://gitee.com/openeuler/kernel/pulls/5564

 

Reviewed-by: Liu YongQiang <liuyongqiang13@huawei.com>
Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com>