drm: bridge: cdns: Kconfig: Switch over dependency to ARCH_K3

With the integration of chip-id detection scheme in kernel[1], there
is no specific need to maintain multitudes of SoC specific config
options, discussed as per [2], we have deprecated the usage in other
places for v5.10-rc1. Fix the missing user so that we can clean up the
configs in v5.11.

[1] drivers/soc/ti/k3-socinfo.c commit 907a2b7e ("soc: ti: add k3 platforms chipid module driver")
[2] https://lore.kernel.org/linux-arm-kernel/20200908112534.t5bgrjf7y3a6l2ss@akan/

Fixes: afba7e6c

 ("drm: bridge: cdns-mhdp8546: Add TI J721E wrapper")
Cc: Swapnil Jakhade <sjakhade@cadence.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Yuti Amonkar <yamonkar@cadence.com>
Cc: Jyri Sarha <jsarha@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20201026165441.22894-1-nm@ti.com