mmc: fsl_esdhc: Fix 'Internal clock never stabilised.' error

Only newer eSDHC controllers set PRSSTAT_SDSTB flag. So do not wait until
flag PRSSTAT_SDSTB is set on old pre-2.2 controllers. Instead sleep for
fixed amount of time like it was before commit 6f883e50 ("mmc:
fsl_esdhc: Add emmc hs200 support").

This change fixes error 'Internal clock never stabilised.' which is printed
on P2020 board at every access to SD card.

Fixes: 6f883e50 ("mmc: fsl_esdhc: Add emmc hs200 support")
Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>
Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>