mtd: spi-nor: Remove unused macro

Remove leftover from nor->cmd_buf.
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>

include/linux/mtd/spi-nor.h

@@ -225,7 +225,6 @@ static inline u8 spi_nor_get_protocol_width(enum spi_nor_protocol proto)
 	return spi_nor_get_protocol_data_nbits(proto);
 }
 
-#define SPI_NOR_MAX_CMD_SIZE	8
 enum spi_nor_ops {
 	SPI_NOR_OPS_READ = 0,
 	SPI_NOR_OPS_WRITE,