docs: security: core.rst: Fix several warnings

Multi-line literal markups only work when they're idented at the
same level, with is not the case here:

   Documentation/security/keys/core.rst:1597: WARNING: Inline literal start-string without end-string.
   Documentation/security/keys/core.rst:1597: WARNING: Inline emphasis start-string without end-string.
   Documentation/security/keys/core.rst:1597: WARNING: Inline emphasis start-string without end-string.
   Documentation/security/keys/core.rst:1598: WARNING: Inline emphasis start-string without end-string.
   Documentation/security/keys/core.rst:1598: WARNING: Inline emphasis start-string without end-string.
   Documentation/security/keys/core.rst:1600: WARNING: Inline literal start-string without end-string.
   Documentation/security/keys/core.rst:1600: WARNING: Inline emphasis start-string without end-string.
   Documentation/security/keys/core.rst:1600: WARNING: Inline emphasis start-string without end-string.
   Documentation/security/keys/core.rst:1600: WARNING: Inline emphasis start-string without end-string.
   Documentation/security/keys/core.rst:1600: WARNING: Inline emphasis start-string without end-string.
   Documentation/security/keys/core.rst:1666: WARNING: Inline literal start-string without end-string.
   Documentation/security/keys/core.rst:1666: WARNING: Inline emphasis start-string without end-string.
   Documentation/security/keys/core.rst:1666: WARNING: Inline emphasis start-string without end-string.
   Documentation/security/keys/core.rst:1666: WARNING: Inline emphasis start-string without end-string.

Fix it by using a code-block instead.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/security/keys/core.rst

@@ -1594,10 +1594,12 @@ The structure has a number of fields, some of which are mandatory:
      attempted key link operation. If there is no match, -EINVAL is returned.
 
 
-  *  ``int (*asym_eds_op)(struct kernel_pkey_params *params,
-			  const void *in, void *out);``
-     ``int (*asym_verify_signature)(struct kernel_pkey_params *params,
-				    const void *in, const void *in2);``
+  *  ``asym_eds_op`` and ``asym_verify_signature``::
+
+       int (*asym_eds_op)(struct kernel_pkey_params *params,
+			  const void *in, void *out);
+       int (*asym_verify_signature)(struct kernel_pkey_params *params,
+				    const void *in, const void *in2);
 
      These methods are optional.  If provided the first allows a key to be
      used to encrypt, decrypt or sign a blob of data, and the second allows a
@@ -1662,8 +1664,10 @@ The structure has a number of fields, some of which are mandatory:
      required crypto isn't available.
 
 
-  *  ``int (*asym_query)(const struct kernel_pkey_params *params,
-			 struct kernel_pkey_query *info);``
+  *  ``asym_query``::
+
+       int (*asym_query)(const struct kernel_pkey_params *params,
+			 struct kernel_pkey_query *info);
 
      This method is optional.  If provided it allows information about the
      public or asymmetric key held in the key to be determined.