ata: pata_pxa: Fix potential NULL pointer dereference in pxa_ata_probe()

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

ata: pata_pxa: Fix potential NULL pointer dereference in pxa_ata_probe()

devm_ioremap() returns NULL on error. Currently, pxa_ata_probe() does

not check for this case, which can result in a NULL pointer dereference.

Add NULL check after devm_ioremap() to prevent this issue.