mtd: spi-nor: sysfs: hide the flash name if not set

The flash name is not reliable as we saw flash ID collisions.
Hide the flash name if not set.

Signed-off-by: JaimeLiao <jaimeliao@mxic.com.tw>
Reviewed-by: Michael Walle <michael@walle.cc>
[ta: update commit subject and description and the sysfs description]
Link: https://lore.kernel.org/r/20231215082138.16063-4-tudor.ambarus@linaro.org
Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>

mtd: spi-nor: sysfs: hide manufacturer if it is not set

The manufacturer may be optional when pure SFDP flashes are supported.
Hide the sysfs property if no manufacturer is set.

Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Reviewed-by: Takahiro Kuwano <Takahiro.Kuwano@infineon.com>
Link: https://lore.kernel.org/r/20220810220654.1297699-3-michael@walle.cc

mtd: spi-nor: hide jedec_id sysfs attribute if not present

Some non-jedec compliant flashes (like the Everspin flashes) don't have
an ID at all. Hide the attribute in this case.

Fixes: 36ac02286265 ("mtd: spi-nor: add initial sysfs support")
Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Reviewed-by: Takahiro Kuwano <Takahiro.Kuwano@infineon.com>
Link: https://lore.kernel.org/r/20220810220654.1297699-2-michael@walle.cc

mtd: spi-nor: add initial sysfs support

Add support to show the manufacturer, the partname and JEDEC identifier
as well as to dump the SFDP table. Not all flashes list their SFDP table
contents in their datasheet. So having that is useful. It might also be
helpful in bug reports from users.

Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Acked-by: Pratyush Yadav <p.yadav@ti.com>