mmc: mmci: stm32: fix max busy timeout calculation

mmc: mmci: stm32: fix max busy timeout calculation

The way that the timeout is currently calculated could lead to a u64
timeout value in mmci_start_command(). This value is then cast in a u32
register that leads to mmc erase failed issue with some SD cards.

Fixes: 8266c585f489 ("mmc: mmci: add hardware busy timeout feature")
Signed-off-by: Yann Gautier <yann.gautier@foss.st.com>
Signed-off-by: Christophe Kerello <christophe.kerello@foss.st.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20230613134146.418016-1-yann.gautier@foss.st.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>