The raw_pylibcpupower.i is removed unexpectedly after 'make mrproper'

We can reproduce the error by performing the following steps:
cd linux-next
make mrproper
cd tools/power/cpupower/bindings/python
make

We will get an error message:
make: *** No rule to make target 'raw_pylibcpupower.i', needed by 'raw_pylibcpupower_wrap.c'.  Stop.

The root cause:

The *.i files are already used for pre-processor output files and
the kernel removes all the *.i files by 'make mrproper'.

That explains why the raw_pylibcpupower.i is removed by 'make mrproper'.

To fix it, Follow John's suggestion to rename raw_pylibcpupower.i to
raw_pylibcpupower.swg.

See:
https://www.swig.org/Doc4.2/SWIG.htmlReviewed-by: John B. Wyatt IV <jwyatt@redhat.com>
Reviewed-by: John B. Wyatt IV <sageofredondo@gmail.com>
Tested-by: John B. Wyatt IV <jwyatt@redhat.com>
Tested-by: John B. Wyatt IV <sageofredondo@gmail.com>
Signed-off-by: Min-Hua Chen <minhuadotchen@gmail.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>