ARM: shmobile: lager-reference: Remove workarounds for core clock issues

Now the core clock issues have been fixed by commit
3c90c55d ("drivers: sh: compile
drivers/sh/pm_runtime.c if ARCH_SHMOBILE_MULTI"), revert the following
2 commits:
  - f98b55d7 ("ARM: shmobile: Add Lager
    clock workarounds for SDHI and MMCIF"),
  - aa5de826 ("ARM: shmobile:
    lager-reference: Work around core clock issues").

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>