mtd: m25p80: Call spi_mem_get_name() to let controller set a custom name

By calling spi_mem_get_name(), the driver of the (Q)SPI controller can
set a custom name for the memory device if necessary.
This is useful to keep mtdparts compatible when controller drivers are
ported from the MTD to the SPI layer.

Suggested-by: Boris Brezillon <boris.brezillon@bootlin.com>
Signed-off-by: Frieder Schrempf <frieder.schrempf@exceet.de>
Acked-by: Boris Brezillon <boris.brezillon@bootlin.com>
Signed-off-by: Mark Brown <broonie@kernel.org>