docs: core-api: avoid using ReST :doc:`foo` markup

The :doc:`foo` tag is auto-generated via automarkup.py.
So, use the filename at the sources, instead of :doc:`foo`.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/d967d490b6655735b7df292f88859b5a1b07d0d7.1623824363.git.mchehab+huawei@kernel.orgSigned-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/core-api/bus-virt-phys-mapping.rst

@@ -8,7 +8,7 @@ How to access I/O mapped memory from within device drivers
 
 	The virt_to_bus() and bus_to_virt() functions have been
 	superseded by the functionality provided by the PCI DMA interface
-	(see :doc:`/core-api/dma-api-howto`).  They continue
+	(see Documentation/core-api/dma-api-howto.rst).  They continue
 	to be documented below for historical purposes, but new code
 	must not use them. --davidm 00/12/12
 

Documentation/core-api/dma-api.rst

@@ -5,7 +5,7 @@ Dynamic DMA mapping using the generic device
 :Author: James E.J. Bottomley <James.Bottomley@HansenPartnership.com>
 
 This document describes the DMA API.  For a more gentle introduction
-of the API (and actual examples), see :doc:`/core-api/dma-api-howto`.
+of the API (and actual examples), see Documentation/core-api/dma-api-howto.rst.
 
 This API is split into two pieces.  Part I describes the basic API.
 Part II describes extensions for supporting non-consistent memory
@@ -479,7 +479,8 @@ without the _attrs suffixes, except that they pass an optional
 dma_attrs.
 
 The interpretation of DMA attributes is architecture-specific, and
-each attribute should be documented in :doc:`/core-api/dma-attributes`.
+each attribute should be documented in
+Documentation/core-api/dma-attributes.rst.
 
 If dma_attrs are 0, the semantics of each of these functions
 is identical to those of the corresponding function

Documentation/core-api/dma-isa-lpc.rst

@@ -17,7 +17,7 @@ To do ISA style DMA you need to include two headers::
 	#include <asm/dma.h>
 
 The first is the generic DMA API used to convert virtual addresses to
-bus addresses (see :doc:`/core-api/dma-api` for details).
+bus addresses (see Documentation/core-api/dma-api.rst for details).
 
 The second contains the routines specific to ISA DMA transfers. Since
 this is not present on all platforms make sure you construct your

Documentation/core-api/index.rst

@@ -48,7 +48,7 @@ Concurrency primitives
 ======================
 
 How Linux keeps everything from happening at the same time.  See
-:doc:`/locking/index` for more related documentation.
+Documentation/locking/index.rst for more related documentation.
 
 .. toctree::
    :maxdepth: 1
@@ -77,7 +77,7 @@ Memory management
 =================
 
 How to allocate and use memory in the kernel.  Note that there is a lot
-more memory-management documentation in :doc:`/vm/index`.
+more memory-management documentation in Documentation/vm/index.rst.
 
 .. toctree::
    :maxdepth: 1