parisc: Fix locking in pdc_iodc_print() firmware call

In the Linux kernel, the following vulnerability has been resolved: parisc: Fix locking in pdc_iodc_print() firmware call Utilize pdc_lock spinlock to protect parallel modifications of the iodc_dbuf[] buffer, check length to prevent buffer overflow of iodc_dbuf[], drop the iodc_retbuf[] buffer and fix some wrong indentings.