mmc: tmio: remove obsolete TMIO_BBS

Since commit 10c7fcbd ("ARM: shmobile: sh7372: Remove ZBOOT
MMC/SDHI support"), this define is not needed anymore.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>