soc: xtensa: rename the cavstool back for backward compatibility

The name change for cavstool.py has also broken the backward
compatibility for SOF testing. Rename cavstool_server.py back
to cavstool.py. Keep the functionality still as same as the previous
one.

And also update the documentation of it.

Signed-off-by: Enjia Mai <enjia.mai@intel.com>

boards/xtensa/intel_adsp_cavs15/doc/index.rst

@@ -76,7 +76,7 @@ Assume that the up_squared board's host name is ``cavs15`` (It also can be an
 ip address), and the user account is ``user``. Then copy the python tool to the
 ``up_squared`` board from your build environment::
 
-   $ scp boards/xtensa/intel_adsp/tools/cavstool_server.py user@cavs15:
+   $ scp boards/xtensa/intel_adsp/tools/cavstool.py user@cavs15:
 
 
 Note that the ``/dev/hda`` device file created by the diagnostic driver must
@@ -85,7 +85,7 @@ loader script as root:
 
 .. code-block:: console
 
-   cavs15$ sudo ./cavstool_server.py
+   cavs15$ sudo ./cavstool.py
 
 Cavstool_server.py is a daemon which accepts a firmware image from a remote host
 and loads it into the ADSP. After successful firmware download, the daemon also

boards/xtensa/intel_adsp_cavs18/doc/generic_intel_adsp.rst

@@ -17,7 +17,7 @@ This documentation describes how to run the intel_adsp_cavs boards. Including:
 Set up the environment
 **********************
 
-1. Copy soc/xtensa/intel_adsp/tools/cavstool_server.py to the target
+1. Copy soc/xtensa/intel_adsp/tools/cavstool.py to the target
    host machine (DUT).
 
 2. In your build machine, install the rimage tool, the signed key and
@@ -34,7 +34,7 @@ Build and run the tests
 
 .. code-block:: console
 
-   sudo ./cavstool_server.py
+   sudo ./cavstool.py
 
 2. Build the application. Take semaphore as an example:
 

boards/xtensa/intel_adsp_cavs25/doc/index.rst

@@ -364,13 +364,13 @@ the Crouton environment installed above.  Copy them:
 
 .. code-block:: console
 
-    dev$ scp boards/xtensa/intel_adsp_cavs15/tools/cavstool_server.py user@crouton:
+    dev$ scp boards/xtensa/intel_adsp_cavs15/tools/cavstool.py user@crouton:
 
 Then start the service in the Crouton environment:
 
 .. code-block:: console
 
-    crouton$ sudo ./cavstool_server.py user@crouton:
+    crouton$ sudo ./cavstool.py user@crouton:
 
 
 Build and Sign Zephyr App