mmc: zynq_sdhci: Fix kernel doc warnings

Fix these kernel doc warnings:
drivers/mmc/zynq_sdhci.c:181: warning: contents before sections
drivers/mmc/zynq_sdhci.c:236: warning: contents before sections
drivers/mmc/zynq_sdhci.c:291: warning: contents before sections
drivers/mmc/zynq_sdhci.c:297: warning: Function parameter or member 'degrees' not described in                   'sdhci_versal_sdcardclk_set_phase'
drivers/mmc/zynq_sdhci.c:354: warning: contents before sections
drivers/mmc/zynq_sdhci.c:360: warning: Function parameter or member 'degrees' not described in                   'sdhci_versal_sampleclk_set_phase'
drivers/mmc/zynq_sdhci.c:467: warning: contents before sections

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Ashok Reddy Soma <ashok.reddy.soma@xilinx.com>
Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>