[PATCH 3/3] mmc: davinci: Handle optional IRQ return value correctly

[Bui Duc Phuc]

> New issues:
> - [Medium] Direct return on `platform_get_irq_optional` error bypasses clock cleanup, leaking the clock enable reference.
>

This will be addressed in v2.

> Pre-existing issues:
> - [High] The driver manually disables the hardware clock in the remove and probe error paths while devm-managed IRQs are still active, risking unclocked register accesses.
> - [High] If DMA descriptor allocation fails, the driver attempts PIO fallback but leaves `host->do_dma` set and leaks the mapped scatterlist.
> - [High] The system suspend routine disables the MMC controller clock without masking the SDIO interrupt, risking unclocked register access.

 These issues are pre-existing, and I’d prefer to keep the scope of
this patch focused on the issue being addressed by this series.