Revert "ata: ahci_platform: convert kcalloc to devm_kcalloc"

Since ahci_platform_put_resources() use target_pwrs after "devm_" freed
it, we cannot use devm_kcalloc for allocating target_pwrs.

This reverts commit bd0038b1.

Reported-and-reviwed-by: Mikko Perttunen <mperttunen@nvidia.com>
Tested-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Corentin Labbe <clabbe@baylibre.com>
Signed-off-by: Tejun Heo <tj@kernel.org>