ARM: shmobile: koelsch-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
3 commits:
  - 4dcb4c80380dfa482874b931e308fd382597feab ("ARM: shmobile: Add Koelsch
    clock workarounds for SDHI"),
  - 8e4f394b20a0fe474dd88204d76978191566decf ("ARM: shmobile:
    koelsch-reference: Annotate clk_enables as __initconst"),
  - 3d75d9ea74fee6f5a4bdcbbdf2d577661d047eef ("ARM: shmobile:
    koelsch-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>