mmc: fsl_esdhc_imx: use VENDORSPEC_FRC_SDCLK_ON to control card clock output

For FSL_USDHC, it do not implement VENDORSPEC_CKEN/PEREN/HCKEN/IPGEN, these
are reserved bits. Instead, use VENDORSPEC_FRC_SDCLK_ON to gate on/off the
card clock output.

After commit b5874b55 ("mmc: fsl_esdhc_imx: add wait_dat0() support"),
we meet SD3.0 card can't work at UHS mode, mmc_switch_voltage() fail because
the second mmc_wait_dat0 return -ETIMEDOUT. According to SD spec, during
voltage switch, need to gate off/on the card clock. If not set the FRC_SDCLK_ON,
after CMD11, hardware will gate off the card clock automatically, so card do
not detect the clock off/on behavior, so will draw the data0 line low until
next command.

Fixes: b5874b55 ("mmc: fsl_esdhc_imx: add wait_dat0() support")
Tested-by: Tim Harvey <tharvey@gateworks.com>
Signed-off-by: Haibo Chen <haibo.chen@nxp.com>