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>
diff --git a/configs/db-88f6820-gp_defconfig b/configs/db-88f6820-gp_defconfig
index ee8cb8a..16417a4 100644
--- a/configs/db-88f6820-gp_defconfig
+++ b/configs/db-88f6820-gp_defconfig
@@ -58,7 +58,7 @@
 CONFIG_ARP_TIMEOUT=200
 CONFIG_NET_RETRY_COUNT=50
 CONFIG_SPL_OF_TRANSLATE=y
-CONFIG_AHCI_MVEBU=y
+CONFIG_AHCI_GENERIC=y
 CONFIG_SYS_I2C_LEGACY=y
 CONFIG_SPL_SYS_I2C_LEGACY=y
 CONFIG_SYS_I2C_MVTWSI=y