media: VIDEO_IMX8_JPEG should depend on ARCH_MXC and not default to m
The i.MX8 QXP/QM integrated JPEG encoder/decoder is only present on
Freescale/NXP i.MX8 QXP and QM SoCs. Hence add a dependency on
ARCH_MXC, to prevent asking the user about this driver when configuring
a kernel without i.MX8 support.
Drop the "default m" (which means "default y" if CONFIG_MODULES is not
enabled), as merely enabling CONFIG_COMPILE_TEST should not enable
additional code.