serial: stm32: Use of_device_get_match_data()

This driver casts away the constness of struct stm32_usart_info that is
pointed to by the of match table. Use of_device_get_match_data() instead
of of_match_device() here and push the const throughout the code so that
we don't cast away const. This nicely avoids referencing the match table
when it is undefined with configurations where CONFIG_OF=n and fixes the
const issues.
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Alexandre Torgue <alexandre.torgue@st.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Frank Rowand <frowand.list@gmail.com>
Cc: <linux-serial@vger.kernel.org>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210123034428.2841052-4-swboyd@chromium.org

drivers/tty/serial/stm32-usart.h

@@ -259,7 +259,7 @@ struct stm32_usart_info stm32h7_info = {
 struct stm32_port {
 	struct uart_port port;
 	struct clk *clk;
-	struct stm32_usart_info *info;
+	const struct stm32_usart_info *info;
 	struct dma_chan *rx_ch;  /* dma rx channel            */
 	dma_addr_t rx_dma_buf;   /* dma rx buffer bus address */
 	unsigned char *rx_buf;   /* dma rx buffer cpu address */