board: tbs2910: Convert pci to driver model

So we can get rid of legacy pci config code.

PCI_PNP is not required for this board, remove it to reduce the size of the
u-boot binary.

DM_PCI does not start the host controller automatically anymore. Do so
in preboot instead.

Signed-off-by: Soeren Moch <smoch@web.de>
diff --git a/configs/tbs2910_defconfig b/configs/tbs2910_defconfig
index 3148a32..98e5ca0 100644
--- a/configs/tbs2910_defconfig
+++ b/configs/tbs2910_defconfig
@@ -9,7 +9,7 @@
 CONFIG_AHCI=y
 CONFIG_BOOTDELAY=3
 CONFIG_USE_PREBOOT=y
-CONFIG_PREBOOT="usb start; if hdmidet; then run set_con_hdmi; else run set_con_serial; fi"
+CONFIG_PREBOOT="echo PCI:; pci enum; pci 1; usb start; if hdmidet; then run set_con_hdmi; else run set_con_serial; fi"
 CONFIG_PRE_CONSOLE_BUFFER=y
 CONFIG_SUPPORT_RAW_INITRD=y
 CONFIG_BOUNCE_BUFFER=y
@@ -54,6 +54,8 @@
 CONFIG_PHYLIB=y
 CONFIG_MII=y
 CONFIG_PCI=y
+CONFIG_DM_PCI=y
+# CONFIG_PCI_PNP is not set
 CONFIG_PINCTRL=y
 CONFIG_PINCTRL_IMX6=y
 CONFIG_DM_RTC=y