dfu: sf: add partition support for nor backend

Copy the partition support from NAND backend to SF,
support part and partubi option.
In case of ubi partition, erase the rest of the
partition as it is mandatory for UBI.

The added code is under compilation flag CONFIG_DFU_SF_PART
activated by default.

for example:

U-Boot> env set dfu_alt_info "spl part 0 1;\
u-boot part 0 2;u-boot-env part 0 3;UBI partubi 0 4"
U-Boot> dfu 0 sf 0:0:10000000:0

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>