Documentation: dynamic_debug: fix a couple of typos

Fix a few "typos" in dynamic-debug-howto.rst.

s/dyndbg_query/ddebug_query/
s/sysfs/debugfs/
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/admin-guide/dynamic-debug-howto.rst

@@ -258,7 +258,7 @@ this boot parameter for debugging purposes.
 
 If ``foo`` module is not built-in, ``foo.dyndbg`` will still be processed at
 boot time, without effect, but will be reprocessed when module is
-loaded later. ``dyndbg_query=`` and bare ``dyndbg=`` are only processed at
+loaded later. ``ddebug_query=`` and bare ``dyndbg=`` are only processed at
 boot.
 
 
@@ -301,7 +301,7 @@ The ``dyndbg`` option is a "fake" module parameter, which means:
 
 For ``CONFIG_DYNAMIC_DEBUG`` kernels, any settings given at boot-time (or
 enabled by ``-DDEBUG`` flag during compilation) can be disabled later via
-the sysfs interface if the debug messages are no longer needed::
+the debugfs interface if the debug messages are no longer needed::
 
    echo "module module_name -p" > <debugfs>/dynamic_debug/control