mmc: tmio: remove TMIO_MMC_HAVE_HIGH_REG flag

TMIO_MMC_HAVE_HIGH_REG is confusing due to its counter-intuitive name.

All the TMIO MMC variants (TMIO MMC, Renesas SDHI, UniPhier SD) actually
have high registers. It is just that each of them implements its own
registers there. The original IP from Panasonic only defines registers
0x00-0xff in the bus_shift=1 review. The register area above them is
platform-dependent.

In fact, TMIO_MMC_HAVE_HIGH_REG is set only by tmio-mmc.c and used to
test the accessibility of CTL_SDIO_REGS. Because it is specific to
the TMIO MFD variant, the right thing to do is to move such registers
to tmio_mmc.c and delete the TMIO_MMC_HAVE_HIGH_REG flag.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>