mtd: devices: fix mchp23k256 read and write

Due to the use of sizeof(), command size set for the spi transfer
was wrong. Driver was sending and receiving always 1 byte less
and especially on write, it was hanging.

echo -n -e "\\x1\\x2\\x3\\x4" > /dev/mtd1

And read part too now works as expected.

hexdump -C -n16 /dev/mtd1
00000000 01 02 03 04 ab f3 ad c2 ab e3 f4 36 dd 38 04 15
00000010

Fixes: 4379075a870b ("mtd: mchp23k256: Add support for mchp23lcv1024")
Signed-off-by: Angelo Dureghello <[e-mail]>
Reviewed-by: Andrew Lunn <[e-mail]>
Signed-off-by: Miquel Raynal <[e-mail]>

drivers/mtd/devices/mchp23k256.c

···
 	struct spi_transfer transfer[2] = {};
 	struct spi_message message;
 	unsigned char command[MAX_CMD_SIZE];
-	int ret;
+	int ret, cmd_len;
 
 	spi_message_init(&message);
+
+	cmd_len = mchp23k256_cmdsz(flash);
 
 	command[0] = MCHP23K256_CMD_WRITE;
 	mchp23k256_addr2cmd(flash, to, command);
 
 	transfer[0].tx_buf = command;
-	transfer[0].len = mchp23k256_cmdsz(flash);
+	transfer[0].len = cmd_len;
 	spi_message_add_tail(&transfer[0], &message);
 
 	transfer[1].tx_buf = buf;
···
 	if (ret)
 		return ret;
 
-	if (retlen && message.actual_length > sizeof(command))
-		*retlen += message.actual_length - sizeof(command);
+	if (retlen && message.actual_length > cmd_len)
+		*retlen += message.actual_length - cmd_len;
 
 	return 0;
 }
···
 	struct spi_transfer transfer[2] = {};
 	struct spi_message message;
 	unsigned char command[MAX_CMD_SIZE];
-	int ret;
+	int ret, cmd_len;
 
 	spi_message_init(&message);
+
+	cmd_len = mchp23k256_cmdsz(flash);
 
 	memset(&transfer, 0, sizeof(transfer));
 	command[0] = MCHP23K256_CMD_READ;
 	mchp23k256_addr2cmd(flash, from, command);
 
 	transfer[0].tx_buf = command;
-	transfer[0].len = mchp23k256_cmdsz(flash);
+	transfer[0].len = cmd_len;
 	spi_message_add_tail(&transfer[0], &message);
 
 	transfer[1].rx_buf = buf;
···
 	if (ret)
 		return ret;
 
-	if (retlen && message.actual_length > sizeof(command))
-		*retlen += message.actual_length - sizeof(command);
+	if (retlen && message.actual_length > cmd_len)
+		*retlen += message.actual_length - cmd_len;
 
 	return 0;
 }