spi: spi_flash: do not fail silently on bad user input

Make sure the user is notified instead of silently returning an error.

Signed-off-by: Liam Beguin <liambeguin@gmail.com>
Reviewed-by: Stephen Warren <swarren@nvidia.com>
diff --git a/drivers/mtd/spi/spi_flash.c b/drivers/mtd/spi/spi_flash.c
index 294d9f9..2e61685 100644
--- a/drivers/mtd/spi/spi_flash.c
+++ b/drivers/mtd/spi/spi_flash.c
@@ -320,7 +320,7 @@
 
 	erase_size = flash->erase_size;
 	if (offset % erase_size || len % erase_size) {
-		debug("SF: Erase offset/length not multiple of erase size\n");
+		printf("SF: Erase offset/length not multiple of erase size\n");
 		return -1;
 	}