drivers: display: gc9x01x: fix correct mipi buffer size

mipi api allows only buffers where pitch is equal to width.
buffers with smaller width get split into multiple transmissions
but mipi buffer size was set incorrectly.

Signed-off-by: Manuel Martin <[email protected]>

Author: Casales

drivers/display/display_gc9x01x.c

@@ -530,7 +530,7 @@ static int gc9x01x_write(const struct device *dev, const uint16_t x, const uint1
 		write_h = 1U;
 		nbr_of_writes = desc->height;
 		mipi_desc.height = 1;
-		mipi_desc.buf_size = desc->pitch * data->bytes_per_pixel;
+		mipi_desc.buf_size = desc->width * data->bytes_per_pixel;
 	} else {
 		write_h = desc->height;
 		mipi_desc.height = desc->height;