This driver was OR'ing desired bits from the existing control setting.
That could create an invalid DPC Trigger Enabled configuration if the
platform previously set this to "ERR_FATAL", 01b.  The driver currently
wants to set this to ERR_NONFATAL/ERR_FATAL, 10b, and the logical OR of
this gets 11b, which is reserved.  Fix that by masking off the fields it is
setting.
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>