Linux Kernel Driver Compilation Error on STM32MP1 - linux

Question

I'm trying to compile a kernel module in Yocto on a STM32MP1 target. I can compile a helloworld example without problem. But as soon as I want to compile following:
#include <linux/platform_device.h>
#include <linux/module.h
#include <linux/types.h>
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Robert W. Oliver II");
MODULE_DESCRIPTION("A simple example Linux module.");
MODULE_VERSION("0.01");
static struct platform_device *pdev;
static int __init fake_eth_add(void)
{
int inst_id = 0;
pdev = platform_device_alloc("fake-eth", inst_id);
return 0;
}
static void __exit fake_eth_put(void)
{
}
module_init(fake_eth_add);
module_exit(fake_eth_put);
I'm getting the following error:
root#txmp-1570:/home/rdm/ethtest# make
make -C /lib/modules/5.7.1/build M=/home/rdm/ethtest modules
make[1]: Entering directory '/lib/modules/5.7.1/build'
MODPOST 1 modules
ERROR: modpost: "platform_device_alloc" [/home/rdm/ethtest/eth-ins.ko] undefined!
make[2]: *** [scripts/Makefile.modpost:94: __modpost] Error 1
make[1]: *** [Makefile:1642: modules] Error 2
make[1]: Leaving directory '/lib/modules/5.7.1/build'
make: *** [Makefile:9: modules] Error 2
The header platform_device.h file is there, but no *.c module as it should be in a platform_device.c file.
My question is, do I need to do any parameter settings in the kernel? If yes, which would it be? So far I didn't find anything with google help regarding platform_device and kernel settings.