mtd: spi-nor: fix kernel-doc for spi_nor::reg_proto

When adding the '{read|write|reg}_proto' fields to 'struct spi_nor', a
colon was missed in the comment for the spi_nor::reg_proto' -- add it.

Fixes: cfc5604c ("mtd: spi-nor: introduce SPI 1-2-2 and SPI 1-4-4 protocols")
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>

include/linux/mtd/spi-nor.h

@@ -347,7 +347,7 @@ struct spi_nor_flash_parameter;
  * @flags:		flag options for the current SPI-NOR (SNOR_F_*)
  * @read_proto:		the SPI protocol for read operations
  * @write_proto:	the SPI protocol for write operations
- * @reg_proto		the SPI protocol for read_reg/write_reg/erase operations
+ * @reg_proto:		the SPI protocol for read_reg/write_reg/erase operations
  * @controller_ops:	SPI NOR controller driver specific operations.
  * @params:		[FLASH-SPECIFIC] SPI-NOR flash parameters and settings.
  *                      The structure includes legacy flash parameters and