crypto: omap-aes - Switch to PIO mode during probe

In cases where requesting for DMA channels fails for some reason, or channel
numbers are not provided in DT or platform data, we switch to PIO-only mode
also checking if platform provides IRQ numbers and interrupt register offsets
in DT and platform data. All dma-only paths are avoided in this mode.

Signed-off-by: Joel Fernandes <joelf@ti.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>