CVE-2021-47169 serial: rp2: use 'request_firmware' instead of 'request_firmware_nowait'

In the Linux kernel, the following vulnerability has been resolved: serial: rp2: use 'requestfirmware' instead of 'requestfirmwarenowait' In 'rp2probe', the driver registers 'rp2uartinterrupt' then calls 'rp2fwcb' through 'requestfirmwarenowait'. In 'rp2fwcb', if the firmware don't exists, functi...