drm/i915/gen11: Add additional pcode status values

I don't think we've ever hit these new error codes, but they're
documented in the gen11 pcode document, so we might as well add them to
the handler.

Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200111014511.2988923-1-matthew.d.roper@intel.com
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>

drivers/gpu/drm/i915/intel_sideband.c

@@ -365,6 +365,10 @@ static inline int gen7_check_mailbox_status(u32 mbox)
 		return -ETIMEDOUT;
 	case GEN7_PCODE_ILLEGAL_DATA:
 		return -EINVAL;
+	case GEN11_PCODE_ILLEGAL_SUBCOMMAND:
+		return -ENXIO;
+	case GEN11_PCODE_LOCKED:
+		return -EBUSY;
 	case GEN7_PCODE_MIN_FREQ_TABLE_GT_RATIO_OUT_OF_RANGE:
 		return -EOVERFLOW;
 	default: