[media] sh_mobile_ceu_camera: Remove dependency on SUPERH

A dependency on ARCH_SHMOBILE seems to be the best option for
sh_mobile_ceu_camera:

* For Super H based SoCs: sh_mobile_ceu is used on SH_AP325RXA, SH_ECOVEC,
  SH_KFR2R09, SH_MIGOR, and SH_7724_SOLUTION_ENGINE which depend on
  CPU_SUBTYPE_SH7722, CPU_SUBTYPE_SH7723, or CPU_SUBTYPE_SH7724 which all
  select ARCH_SHMOBILE.

* For ARM Based SoCs: Since the removal of legacy (non-multiplatform)
  support this driver has not been used by any Renesas ARM based SoCs.
  The Renesas ARM based SoCs currently select ARCH_SHMOBILE, however,
  it is planned that this will no longer be the case.

This is part of an ongoing process to migrate from ARCH_SHMOBILE to
ARCH_RENESAS the motivation for which being that RENESAS seems to be a more
appropriate name than SHMOBILE for the majority of Renesas ARM based SoCs.

Thanks to Geert Uytterhoeven for analysis and portions of the
change log text.

Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>