spi: atmel-quadspi: Make atmel_qspi_get_name static

Fix sparse warning:

drivers/spi/atmel-quadspi.c:369:12: warning:
 symbol 'atmel_qspi_get_name' was not declared. Should it be static?
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/atmel-quadspi.c

@@ -366,7 +366,7 @@ static int atmel_qspi_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
 	return err;
 }
 
-const char *atmel_qspi_get_name(struct spi_mem *spimem)
+static const char *atmel_qspi_get_name(struct spi_mem *spimem)
 {
 	return dev_name(spimem->spi->dev.parent);
 }