[Blackfin] serial driver: Add flow control support to bf54x

Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>

diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 202fb5c..cf627cd 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -699,14 +699,14 @@
 
 config UART1_CTS_PIN
 	int "UART1 CTS pin"
-	depends on BFIN_UART1_CTSRTS && (BF53x || BF561)
+	depends on BFIN_UART1_CTSRTS && !BF54x
 	default -1
 	help
 	  Refer to ./include/asm-blackfin/gpio.h to see the GPIO map.
 
 config UART1_RTS_PIN
 	int "UART1 RTS pin"
-	depends on BFIN_UART1_CTSRTS && (BF53x || BF561)
+	depends on BFIN_UART1_CTSRTS && !BF54x
 	default -1
 	help
 	  Refer to ./include/asm-blackfin/gpio.h to see the GPIO map.