mtd: spi-nor: Emphasise which is the generic set_4byte_addr_mode() method

Rename (*set_4byte)() to (*set_4byte_addr_mode)() for a better
differentiation between the 4 byte address mode and opcodes.

Rename macronix_set_4byte() to spi_nor_set_4byte_addr_mode(), it will be
the only 4 byte address mode method exposed to the manufacturer drivers.

Here's how the manufacturers enter and exit the 4 byte address mode:
- eon, gidadevice, issi, macronix, xmc use EN4B/EX4B
- micron-st needs WEN. st_micron_set_4byte_addr_mode() will become
  a private method, as they are the only ones that need WEN before the
  EN4B/EX4B commands.
- newer spansion have a 4BAM opcode (this translates to a new, public
  command). Older spansion  flashes use the BRWR command (legacy in
  core.c -> spansion_set_4byte_addr_mode())
- winbond's method is hackish and may be reason for just a flash
  fixup hook -> private method

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Reviewed-by: Vignesh Raghavendra <vigneshr@ti.com>

include/linux/mtd/spi-nor.h

@@ -520,7 +520,7 @@ struct spi_nor_locking_ops {
  * @erase_map:		the erase map parsed from the SFDP Sector Map Parameter
  *                      Table.
  * @quad_enable:	enables SPI NOR quad mode.
- * @set_4byte:		puts the SPI NOR in 4 byte addressing mode.
+ * @set_4byte_addr_mode: puts the SPI NOR in 4 byte addressing mode.
  * @convert_addr:	converts an absolute address into something the flash
  *                      will understand. Particularly useful when pagesize is
  *                      not a power-of-2.
@@ -541,7 +541,7 @@ struct spi_nor_flash_parameter {
 	struct spi_nor_erase_map        erase_map;
 
 	int (*quad_enable)(struct spi_nor *nor);
-	int (*set_4byte)(struct spi_nor *nor, bool enable);
+	int (*set_4byte_addr_mode)(struct spi_nor *nor, bool enable);
 	u32 (*convert_addr)(struct spi_nor *nor, u32 addr);
 	int (*setup)(struct spi_nor *nor, const struct spi_nor_hwcaps *hwcaps);