ARM: shmobile: fix build regressions

A number of Kconfig options have become available now to random ARM
platforms outside of ARCH_MULTIPLATFORM, which now causes Kconfig
warnings, and other build errors when those select options that
lack additional dependencies, e.g.:

WARNING: unmet direct dependencies detected for HAVE_ARM_ARCH_TIMER
  Depends on [n]: CPU_V7 [=n]
  Selected by [y]:
  - ARCH_RCAR_GEN2 [=y] && SOC_RENESAS [=y]
  - ARCH_R8A73A4 [=y] && SOC_RENESAS [=y] && ARM [=y]

WARNING: unmet direct dependencies detected for SYS_SUPPORTS_EM_STI
  Depends on [n]: GENERIC_CLOCKEVENTS [=n]
  Selected by [y]:
  - ARCH_EMEV2 [=y] && SOC_RENESAS [=y] && ARM [=y]

Put the old dependency on ARCH_RENESAS back for the moment to restore
the previous behavior.

Fixes: 062887bf ("ARM: shmobile: Move SoC Kconfig symbols to drivers/soc/renesas/")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>