pds_core: quiesce DMA before freeing resources

In the Linux kernel, the following vulnerability has been resolved: pds_core: quiesce DMA before freeing resources pdsc_teardown() frees DMA buffers but does not disable bus mastering, leaving the device able to perform DMA after the buffers are freed. This can lead to use-after-free if the device writes to freed memory. Add pci_clear_master() to pdsc_teardown() to disable bus mastering before freeing resources, ensuring all DMA is quiesced. Add pci_set_master() to pdsc_setup() to re-enable bus mastering, which is needed for the firmware recovery path since pdsc_teardown() now disables it.

Where it's fixed