mmc: davinci: Fix -Wpointer-to-int-cast on compile test

mmc: davinci: Fix -Wpointer-to-int-cast on compile test

Store in interrupt service routine always '1' in end_command, not the
value of host->cmd to fix compile test warnings on RISC-V:

  drivers/mmc/host/davinci_mmc.c:999:17: warning:
    cast from pointer to integer of different size [-Wpointer-to-int-cast]

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Link: https://lore.kernel.org/r/20200902204847.2764-1-krzk@kernel.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>