mmc: fsl_esdhc_imx: remove the 1ms delay before sending command

This 1ms delay before sending command already exist from the beginning
of the fsl_esdhc driver added in year 2008. Now this driver has been
split for two files: fsl_esdhc.c and fsl_esdhc_imx.c. fsl_esdhc_imx.c
only for i.MX series. i.MX series esdhc/usdhc do not need this 1ms delay
before sending any command. So remove this 1ms, this will save a lot
time if handling a large mmc data.

Signed-off-by: Haibo Chen <haibo.chen@nxp.com>