spi: spi-cadence-quadspi: Populate get_name() interface

Implement get_name() interface of spi_controller_mem_ops so as to avoid
changing of mtd->name due to driver being moved over to spi-mem
framework from SPI NOR. This avoids breaking of MTD cmdline args being
passed by bootloaders which maybe using old driver name.

Fixes: 31fb632b ("spi: Move cadence-quadspi driver to drivers/spi/")
Reported-by: Jan Kiszka <jan.kiszka@siemens.com>
Suggested-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Link: https://lore.kernel.org/r/20200825172506.14375-1-vigneshr@ti.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-cadence-quadspi.c

@@ -1128,8 +1128,17 @@ static int cqspi_request_mmap_dma(struct cqspi_st *cqspi)
 	return 0;
 }
 
+static const char *cqspi_get_name(struct spi_mem *mem)
+{
+	struct cqspi_st *cqspi = spi_master_get_devdata(mem->spi->master);
+	struct device *dev = &cqspi->pdev->dev;
+
+	return devm_kasprintf(dev, GFP_KERNEL, "%s.%d", dev_name(dev), mem->spi->chip_select);
+}
+
 static const struct spi_controller_mem_ops cqspi_mem_ops = {
 	.exec_op = cqspi_exec_mem_op,
+	.get_name = cqspi_get_name,
 };
 
 static int cqspi_setup_flash(struct cqspi_st *cqspi)