Add option to the mmc rd test to check the duration of the
execution of the mmc read command. This allows intercepting
read performance regressions.
Signed-off-by: NMarek Vasut <marek.vasut+renesas@gmail.com>
Cc: Tom Rini <trini@konsulko.com>
Cc: Simon Glass <sjg@chromium.org>
Reviewed-by: NSimon Glass <sjg@chromium.org>