tests: driver: dma test case loop_transfer fails on stm32 with dmamux

[FRASTM]

Describe the bug
When the stm32 has a dmamux, the request ID 0 is not accessible, causing a failure in the memory-to-memory testing.
The test cases tests/drivers/dma/loop_transfer and tests/drivers/dma/chan_blen_transfer are failed
especially on nucleo_g474re, nucleo_wb55rg, nucleo_g071rb

To Reproduce
Steps to reproduce the behavior:

1. west build -p auto -b nucleo_g474re tests/drivers/dma/loop_transfer/

Expected behavior
test PASSED

Logs and console output

Running test suite dma_m2m_loop_test                                            
===================================================================             
START - test_dma_m2m_loop                                                       
DMA memory to memory transfer started on DMAMUX_1                               
Preparing DMA Controller                                                        
this platform do not support the dma channel                                    
Starting the transfer on channel 2 and waiting for 1 second                     
E: request ID 0 is not valid.                                                   
ERROR: transfer config (2)                                                      
                                                                                
    Assertion failed at WEST_TOPDIR/zephyr/tests/drivers/dma/loop_transfer/src/e
                                                                                
 FAIL - test_dma_m2m_loop in 0.35 seconds                                       
===================================================================             
Test suite dma_m2m_loop_test failed.                                            
===================================================================             
PROJECT EXECUTION FAILED                                                        

Environment (please complete the following information):

• Commit SHA f05ea67

[FRASTM]

FIXED by #34972