CONFIG_USB_IMX21_HCD should be handled in generic config and
module package. So moved it into generic config.
This also fixed build issue (kernel config question) of layerscape
armv8_32b since it also used ARCH_MXC.
Signed-off-by: Yangbo Lu <yangbo.lu@nxp.com>
[Deactivate CONFIG_USB_IMX21_HCD also for kernel 4.19]
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>