acpi, nfit: hide unknown commands from nmemX/commands

For vendor specific commands that do not have a common kernel
translation, hide them from nmemX/commands. For example, the following
results from new enabling to probe for support of the new
NVDIMM_FAMILY_INTEL DSMs specified in v1.6 of the command specification
[1]:

    # cat /sys/bus/nd/devices/nmem0/commands
    smart smart_thresh flags get_size get_data set_data effect_size
    effect_log vendor cmd_call unknown unknown unknown unknown unknown
    unknown unknown unknown

[1]: https://pmem.io/documents/NVDIMM_DSM_Interface-V1.6.pdf

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
index ebe0857..444832b 100644
--- a/drivers/acpi/nfit/core.c
+++ b/drivers/acpi/nfit/core.c
@@ -1769,8 +1769,14 @@
 		 * userspace interface.
 		 */
 		cmd_mask = 1UL << ND_CMD_CALL;
-		if (nfit_mem->family == NVDIMM_FAMILY_INTEL)
-			cmd_mask |= nfit_mem->dsm_mask;
+		if (nfit_mem->family == NVDIMM_FAMILY_INTEL) {
+			/*
+			 * These commands have a 1:1 correspondence
+			 * between DSM payload and libnvdimm ioctl
+			 * payload format.
+			 */
+			cmd_mask |= nfit_mem->dsm_mask & NVDIMM_STANDARD_CMDMASK;
+		}
 
 		if (nfit_mem->has_lsi)
 			set_bit(ND_CMD_GET_CONFIG_SIZE, &cmd_mask);