usb: gadget: fsl: Re-enable driver for ARM SoCs

usb: gadget: fsl: Re-enable driver for ARM SoCs

The commit a390bef7db1f ("usb: gadget: fsl_mxc_udc: Remove the driver")
dropped the ARCH_MXC dependency from USB_FSL_USB2, leaving it depending
solely on FSL_SOC.

FSL_SOC is powerpc only; it was briefly available on ARM in 2014 but was
removed by commit cfd074ad8600 ("ARM: imx: temporarily remove
CONFIG_SOC_FSL from LS1021A"). Therefore the driver can no longer be
enabled on ARM platforms.

This appears to be a mistake as arm64's ARCH_LAYERSCAPE and arm32
SOC_LS1021A SoCs use this symbol. It's enabled in these defconfigs:

arch/arm/configs/imx_v6_v7_defconfig:CONFIG_USB_FSL_USB2=y
arch/arm/configs/multi_v7_defconfig:CONFIG_USB_FSL_USB2=y
arch/powerpc/configs/mgcoge_defconfig:CONFIG_USB_FSL_USB2=y
arch/powerpc/configs/mpc512x_defconfig:CONFIG_USB_FSL_USB2=y

To fix, expand the dependencies so USB_FSL_USB2 can be enabled on the
ARM platforms, and with COMPILE_TEST.

Fixes: a390bef7db1f ("usb: gadget: fsl_mxc_udc: Remove the driver")
Signed-off-by: Joel Stanley <joel@jms.id.au>
Link: https://lore.kernel.org/r/20210610034957.93376-1-joel@jms.id.au
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>