fsl_esdhc: fix wrong clock mask

Fix typo in SYSCTL_CLOCK_MASK, which caused residual in high bits of SDCLKFS.

Signed-off-by: Jin Qing <B24347@freescale.com>
Signed-off-by: Li Yang <leoli@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>