mmc: dw_mmc: socfpga: move socfpga private init

Currently platform specific private data initialization is done by
dw_mci_socfpga_priv_init and dw_mci_socfpga_parse_dt. As we already have
separate platform specific device tree parser dw_mci_socfpga_parse_dt,
move the dw_mci_socfpga_priv_init code to dw_mci_socfpga_parse_dt.
We can use the dw_mci_socfpga_priv_init to do some actual platform
specific initialization.

Signed-off-by: Yuvaraj Kumar C D <yuvaraj.cd@samsung.com>
Tested-by: Alim Akhtar <alim.akhtar@samsung.com>
Tested-by: Jaehoon Chung <jh80.chung@samsung.com>
Acked-by: Seungwon Jeon <tgih.jun@samsung.com>
Signed-off-by: Chris Ball <cjb@laptop.org>