layerscape: armv7: activate USB support.

The feature flags say that this target supports USB so packages
depending on USB are being build, but actually the kernel configuration
misses USB support. It looks like this SoC supports USB, so activate it.

Signed-off-by: Hauke Mehrtens <[email protected]>

target/linux/layerscape/armv7/config-4.9

@@ -904,6 +904,7 @@ CONFIG_UCS2_STRING=y
 CONFIG_UEVENT_HELPER_PATH=""
 CONFIG_UNCOMPRESS_INCLUDE="debug/uncompress.h"
 CONFIG_UNIX_DIAG=y
+CONFIG_USB_SUPPORT=y
 CONFIG_USER_NS=y
 CONFIG_USE_OF=y
 CONFIG_UTS_NS=y