drivers: ata: Rename ahci_mvebu

drivers: ata: Rename ahci_mvebu

Rename 'ahci_mvebu' to 'ahci_generic' and select it by default.
The AHCI driver contains no SoC specific code and only expects the
base address to be passed, thus rename it to ahci_generic and add the
DT compatible string "generic-ahci".

Update existing defconfigs to use the new Kconfig name as well.

TEST: Booted on QEMU sbsa using the generic-ahci node.

Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-by: Stefan Roese <sr@denx.de>
Cc: Tom Rini <trini@konsulko.com>
Cc: Stefan Roese <sr@denx.de>
Acked-by: Tony Dinh <mibodhi@gmail.com>