mmc: tmio: Replace ifdeffery with IS_ENABLED/CONFIG_IS_ENABLED macros

Instead of #if and #ifdef, use IS_ENABLED and CONFIG_IS_ENABLED macros.
This improves build test coverage. The CONFIG_SPL_BUILD must remain an
ifdef, as CONFIG_SPL_STACK may not always be defined, e.g. in U-Boot
proper build. No functional change.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>