libnvdimm/security: Fix key lookup permissions

As of commit 8c0637e950 ("keys: Make the KEY_NEED_* perms an enum rather
than a mask") lookup_user_key() needs an explicit declaration of what it
wants to do with the key. Add KEY_NEED_SEARCH to fix a warning with the
below signature, and fixes the inability to retrieve a key.

    WARNING: CPU: 15 PID: 6276 at security/keys/permission.c:35 key_task_permission+0xd3/0x140
    [..]
    RIP: 0010:key_task_permission+0xd3/0x140
    [..]
    Call Trace:
     lookup_user_key+0xeb/0x6b0
     ? vsscanf+0x3df/0x840
     ? key_validate+0x50/0x50
     ? key_default_cmp+0x20/0x20
     nvdimm_get_user_key_payload.part.0+0x21/0x110 [libnvdimm]
     nvdimm_security_store+0x67d/0xb20 [libnvdimm]
     security_store+0x67/0x1a0 [libnvdimm]
     kernfs_fop_write+0xcf/0x1c0
     vfs_write+0xde/0x1d0
     ksys_write+0x68/0xe0
     do_syscall_64+0x5c/0xa0
     entry_SYSCALL_64_after_hwframe+0x49/0xb3

Fixes: 8c0637e950 ("keys: Make the KEY_NEED_* perms an enum rather than a mask")
Suggested-by: David Howells <dhowells@redhat.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Link: https://lore.kernel.org/r/159297332630.1304143.237026690015653759.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/nvdimm/security.c

@@ -95,7 +95,7 @@ static struct key *nvdimm_lookup_user_key(struct nvdimm *nvdimm,
 	struct encrypted_key_payload *epayload;
 	struct device *dev = &nvdimm->dev;
 
-	keyref = lookup_user_key(id, 0, 0);
+	keyref = lookup_user_key(id, 0, KEY_NEED_SEARCH);
 	if (IS_ERR(keyref))
 		return NULL;