mmc: Fix timeout values passed to mmc_wait_dat0()

mmc_wait_dat0() expects timeout argument to be in usec units. But some
overlying functions operate on timeout in msec units. Convert timeout
from msec to usec when passing it to mmc_wait_dat0().

This fixes 'avb' commands on BeagleBoard X15, because next chain was
failing:

    get_partition() -> mmc_switch_part() -> __mmc_switch() ->
    mmc_wait_dat0()

when passing incorrect timeout from __mmc_switch() to mmc_wait_dat0().

Fixes: bb98b8c5c06a ("mmc: During a switch, poll on dat0 if available and check the final status")
Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
Reviewed-by: Eugeniu Rosca <rosca.eugeniu@gmail.com>
Tested-by: Eugeniu Rosca <rosca.eugeniu@gmail.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
Tested-by: Igor Opaniuk <igor.opaniuk@gmail.com>
Reviewed-by: Igor Opaniuk <igor.opaniuk@gmail.com>