mmc: tmio: add new TMIO_MMC_HAVE_HIGH_REG flags

The accessibility checking method to the higher register was added by
69d1fe18 (mmc: tmio: only access registers above 0xff, if available)
But, it doesn't care 32bit register.  It is impossible to calculate it
from the resource size, since there is 16/32 bit register IP (e.g. VERSION
is located on 0xe2 if 16bit register, but it is located on 0x1c4 if 32bit
register).

This patch adds new TMIO_MMC_HAVE_HIGH_REG flags, tmio_mmc driver has it,
and sh_mobile_sdhi doesn't have it today.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Chris Ball <cjb@laptop.org>