mtd: spi-nor-core: Use dev_err for reporting erase/write failures

Use dev_err() when reporting reason for erase/write failures so that
users can be made aware of the reason for failure.

Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
diff --git a/drivers/mtd/spi/spi-nor-core.c b/drivers/mtd/spi/spi-nor-core.c
index 990e39d..1eebbcb 100644
--- a/drivers/mtd/spi/spi-nor-core.c
+++ b/drivers/mtd/spi/spi-nor-core.c
@@ -380,12 +380,12 @@
 
 	if (fsr & (FSR_E_ERR | FSR_P_ERR)) {
 		if (fsr & FSR_E_ERR)
-			dev_dbg(nor->dev, "Erase operation failed.\n");
+			dev_err(nor->dev, "Erase operation failed.\n");
 		else
-			dev_dbg(nor->dev, "Program operation failed.\n");
+			dev_err(nor->dev, "Program operation failed.\n");
 
 		if (fsr & FSR_PT_ERR)
-			dev_dbg(nor->dev,
+			dev_err(nor->dev,
 				"Attempted to modify a protected sector.\n");
 
 		nor->write_reg(nor, SPINOR_OP_CLFSR, NULL, 0);