driver: wifi: eswifi: Fix spi buffer length

The eswifi spi driver sets up spi buffer length as number of frames,
but the length shall be number of bytes. Because eswifi use 16 bit as
frame size, so this turns out reading and writing half of data and
fails to sending any at command request and getting any responds from
eswifi module.

Fix it by setting up length as number of bytes.

Fixes zephyrproject-rtos#62056

Signed-off-by: Chien Hung Lin <chienhung.lin.tw@gmail.com>

drivers/wifi/eswifi/eswifi_bus_spi.c

@@ -66,7 +66,7 @@ static int eswifi_spi_write(struct eswifi_dev *eswifi, char *data, size_t dlen)
 	int status;
 
 	spi_tx_buf[0].buf = data;
-	spi_tx_buf[0].len = dlen / 2; /* 16-bit words */
+	spi_tx_buf[0].len = dlen;
 	spi_tx.buffers = spi_tx_buf;
 	spi_tx.count = ARRAY_SIZE(spi_tx_buf);
 
@@ -88,7 +88,7 @@ static int eswifi_spi_read(struct eswifi_dev *eswifi, char *data, size_t dlen)
 	int status;
 
 	spi_rx_buf[0].buf = data;
-	spi_rx_buf[0].len = dlen / 2; /* 16-bit words */
+	spi_rx_buf[0].len = dlen;
 	spi_rx.buffers = spi_rx_buf;
 	spi_rx.count = ARRAY_SIZE(spi_rx_buf);