Convert CONFIG_USB_MAX_CONTROLLER_COUNT to Kconfig

This converts the following to Kconfig:
   CONFIG_USB_MAX_CONTROLLER_COUNT

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/T1042D4RDB_defconfig b/configs/T1042D4RDB_defconfig
index f05e66e..ae2f005 100644
--- a/configs/T1042D4RDB_defconfig
+++ b/configs/T1042D4RDB_defconfig
@@ -91,6 +91,7 @@
 CONFIG_FSL_ESPI=y
 CONFIG_USB=y
 CONFIG_USB_EHCI_FSL=y
+CONFIG_USB_MAX_CONTROLLER_COUNT=2
 CONFIG_USB_STORAGE=y
 CONFIG_ADDR_MAP=y
 CONFIG_SYS_NUM_ADDR_MAP=64