mmc: omap_hsmmc: simplify card/cover detect isr

strip the card dectet logic from cover detect isr and vice versa
the generic mmc_gpio_cd_irqt isr, uses 200ms on removal/insertion,
hence that should be fine here as well

Signed-off-by: Andreas Fenkart <afenkart@gmail.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>