nvmem: qfprom: remove incorrect write support

qfprom has different address spaces for read and write. Reads are
always done from corrected address space, where as writes are done
on raw address space.
Writing to corrected address space is invalid and ignored, so it
does not make sense to have this support in the driver which only
supports corrected address space regions at the moment.

Fixes: 4ab1199 ("nvmem: qfprom: Add Qualcomm QFPROM support.")
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200522113341.7728-1-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/nvmem/qfprom.c

@@ -27,25 +27,11 @@ static int qfprom_reg_read(void *context,
 	return 0;
 }
 
-static int qfprom_reg_write(void *context,
-			 unsigned int reg, void *_val, size_t bytes)
-{
-	struct qfprom_priv *priv = context;
-	u8 *val = _val;
-	int i = 0, words = bytes;
-
-	while (words--)
-		writeb(*val++, priv->base + reg + i++);
-
-	return 0;
-}
-
 static struct nvmem_config econfig = {
 	.name = "qfprom",
 	.stride = 1,
 	.word_size = 1,
 	.reg_read = qfprom_reg_read,
-	.reg_write = qfprom_reg_write,
 };
 
 static int qfprom_probe(struct platform_device *pdev)