drm/i915/dmc: s/intel_csr.c/intel_dmc.c and s/intel_csr.h/intel_dmc.h

Finally, rename the header and source file from csr to dmc.

v2: Add file rename in Documentation.
- Place headers in orders. (Jani)

Cc: Jani Nikula <jani.nikula@linux.intel.com>
Signed-off-by: Anusha Srivatsa <anusha.srivatsa@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210518213444.11420-6-anusha.srivatsa@intel.com
diff --git a/Documentation/gpu/i915.rst b/Documentation/gpu/i915.rst
index 486c720..42ce019 100644
--- a/Documentation/gpu/i915.rst
+++ b/Documentation/gpu/i915.rst
@@ -210,13 +210,13 @@
 .. kernel-doc:: drivers/gpu/drm/i915/display/intel_dpio_phy.c
    :doc: DPIO
 
-CSR firmware support for DMC
-----------------------------
+DMC Firmware Support
+--------------------
 
-.. kernel-doc:: drivers/gpu/drm/i915/display/intel_csr.c
-   :doc: csr support for dmc
+.. kernel-doc:: drivers/gpu/drm/i915/display/intel_dmc.c
+   :doc: DMC Firmware Support
 
-.. kernel-doc:: drivers/gpu/drm/i915/display/intel_csr.c
+.. kernel-doc:: drivers/gpu/drm/i915/display/intel_dmc.c
    :internal:
 
 Video BIOS Table (VBT)
@@ -537,7 +537,7 @@
 
 DMC
 ---
-See `CSR firmware support for DMC`_
+See `DMC Firmware Support`_
 
 Tracing
 =======