pci: ftpci100: add new driver implementation

Add a new DM driver supporting FTPCI100 IP used in SoC designs.
This implementation is not based on the old non-DM ftpci100 code
dropped from U-Boot.

Enable the driver in sandbox_defconfig to test compilability.

Signed-off-by: Sergei Antonov <saproj@gmail.com>
diff --git a/configs/sandbox_defconfig b/configs/sandbox_defconfig
index f031b50..259f31f 100644
--- a/configs/sandbox_defconfig
+++ b/configs/sandbox_defconfig
@@ -231,6 +231,7 @@
 CONFIG_NVME_PCI=y
 CONFIG_PCI_REGION_MULTI_ENTRY=y
 CONFIG_PCI_SANDBOX=y
+CONFIG_PCI_FTPCI100=y
 CONFIG_PHY=y
 CONFIG_PHY_SANDBOX=y
 CONFIG_PINCTRL=y