mmc: mmci: stm32: fix DMA API overlapping mappings warning

In the Linux kernel, the following vulnerability has been resolved:

mmc: mmci: stm32: fix DMA API overlapping mappings warning

Turning on CONFIG_DMA_API_DEBUG_SG results in the following warning:

DMA-API: mmci-pl18x 48220000.mmc: cacheline tracking EEXIST,
overlapping mappings aren't supported
WARNING: CPU: 1 PID: 51 at kernel/dma/debug.c:568
add_dma_entry+0x234/0x2f4
Modules linked in:
CPU: 1 PID: 51 Comm: kworker/1:2 Not tainted 6.1.28 #1
Hardware name: STMicroelectronics STM32MP257F-EV1 Evaluation Board (DT)
Workqueue: events_freezable mmc_rescan
Call trace:
add_dma_entry+0x234/0x2f4
debug_dma_map_sg+0x198/0x350
__dma_map_sg_attrs+0xa0/0x110
dma_map_sg_attrs+0x10/0x2c
sdmmc_idma_prep_data+0x80/0xc0
mmci_prep_data+0x38/0x84
mmci_start_data+0x108/0x2dc
mmci_request+0xe4/0x190
__mmc_start_request+0x68/0x140
mmc_start_request+0x94/0xc0
mmc_wait_for_req+0x70/0x100
mmc_send_tuning+0x108/0x1ac
sdmmc_execute_tuning+0x14c/0x210
mmc_execute_tuning+0x48/0xec
mmc_sd_init_uhs_card.part.0+0x208/0x464
mmc_sd_init_card+0x318/0x89c
mmc_attach_sd+0xe4/0x180
mmc_rescan+0x244/0x320

DMA API debug brings to light leaking dma-mappings as dma_map_sg and
dma_unmap_sg are not correctly balanced.

If an error occurs in mmci_cmd_irq function, only mmci_dma_error
function is called and as this API is not managed on stm32 variant,
dma_unmap_sg is never called in this error path.