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>
diff --git a/drivers/dfu/Kconfig b/drivers/dfu/Kconfig
index 4692736..1cbec81 100644
--- a/drivers/dfu/Kconfig
+++ b/drivers/dfu/Kconfig
@@ -46,5 +46,13 @@
 	  This option enables using DFU to read and write to SPI flash based
 	  storage.
 
+config DFU_SF_PART
+	bool "MTD partition support for SPI flash back end"
+	depends on DFU_SF && CMD_MTDPARTS
+	default y
+	help
+	  This option enables the support of "part" and "partubi" target in
+	  SPI flash DFU back end.
+
 endif
 endmenu