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.

Fixes: 2db16c6e ("media: imx-jpeg: Add V4L2 driver for i.MX8 JPEG Encoder/Decoder")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>