staging: fbtft: Follow renaming of SPI "master" to "controller"

In commit 8caab75f ("spi: Generalize SPI "master" to "controller"")
some functions and struct members were renamed. To not break all drivers
compatibility macros were provided.

To be able to remove these compatibility macros push the renaming into
this driver.
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/df79f22caf31d2c5ca2b15b33670323d1e1120c7.1707324794.git.u.kleine-koenig@pengutronix.deSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/staging/fbtft/fbtft-core.c

@@ -794,7 +794,7 @@ int fbtft_register_framebuffer(struct fb_info *fb_info)
 	if (par->txbuf.buf && par->txbuf.len >= 1024)
 		sprintf(text1, ", %zu KiB buffer memory", par->txbuf.len >> 10);
 	if (spi)
-		sprintf(text2, ", spi%d.%d at %d MHz", spi->master->bus_num,
+		sprintf(text2, ", spi%d.%d at %d MHz", spi->controller->bus_num,
 			spi_get_chipselect(spi, 0), spi->max_speed_hz / 1000000);
 	dev_info(fb_info->dev,
 		 "%s frame buffer, %dx%d, %d KiB video memory%s, fps=%lu%s\n",
@@ -1215,7 +1215,7 @@ int fbtft_probe_common(struct fbtft_display *display,
 
 	/* 9-bit SPI setup */
 	if (par->spi && display->buswidth == 9) {
-		if (par->spi->master->bits_per_word_mask & SPI_BPW_MASK(9)) {
+		if (par->spi->controller->bits_per_word_mask & SPI_BPW_MASK(9)) {
 			par->spi->bits_per_word = 9;
 		} else {
 			dev_warn(&par->spi->dev,