nand: vybrid: Re-introduce vf610_nfc.dev

nand: vybrid: Re-introduce vf610_nfc.dev

This member was presumably dropped when this driver was converted from
Linux. However, it is still used in log statements during initialization.
This patch adds the member back. In addition, allocation of struct
vf610_nfc has been moved to the callers of vf610_nfc_nand_init. This allows
it to be allocated by DM (if it is being used) and for dev to be
initialized.

Signed-off-by: Sean Anderson <seanga2@gmail.com>
Tested-by: Patrick Delaunay <patrick.delaunay@st.com>