dts_fixups: Use DT_ prefix in all defined labels not related to Kconfig

These changes were obtained by running a script  created by
Ulf Magnusson <Ulf.Magnusson@nordicsemi.no> for the following
specification:

1. Read the contents of all dts_fixup.h files in Zephyr
2. Check the left-hand side of the #define macros (i.e. the X in
   #define X Y)
3. Check if that name is also the name of a Kconfig option
   3.a If it is, then do nothing
   3.b If it is not, then replace CONFIG_ with DT_ or add DT_ if it
       has neither of these two prefixes
4. Replace the use of the changed #define in the code itself
   (.c, .h, .ld)

Additionally, some tweaks had to be added to this script to catch some
of the macros used in the code in a parameterized form, e.g.:
- CONFIG_GPIO_STM32_GPIO##__SUFFIX##_BASE_ADDRESS
- CONFIG_UART_##idx##_TX_PIN
- I2C_SBCON_##_num##_BASE_ADDR
and to prevent adding DT_ prefix to the following symbols:
- FLASH_START
- FLASH_SIZE
- SRAM_START
- SRAM_SIZE
- _ROM_ADDR
- _ROM_SIZE
- _RAM_ADDR
- _RAM_SIZE
which are surprisingly also defined in some dts_fixup.h files.

Finally, some manual corrections had to be done as well:
- name##_IRQ -> DT_##name##_IRQ in uart_stm32.c

Signed-off-by: Andrzej Głąbek <andrzej.glabek@nordicsemi.no>

drivers/serial/uart_stm32.c

@@ -372,11 +372,11 @@ static int uart_stm32_init(struct device *dev)
 #define STM32_UART_IRQ_HANDLER(name)					\
 static void uart_stm32_irq_config_func_##name(struct device *dev)	\
 {									\
-	IRQ_CONNECT(name##_IRQ,					\
-		CONFIG_UART_STM32_##name##_IRQ_PRI,			\
+	IRQ_CONNECT(DT_##name##_IRQ,					\
+		DT_UART_STM32_##name##_IRQ_PRI,			\
 		uart_stm32_isr, DEVICE_GET(uart_stm32_##name),	\
 		0);							\
-	irq_enable(name##_IRQ);					\
+	irq_enable(DT_##name##_IRQ);					\
 }
 #else
 #define STM32_UART_IRQ_HANDLER_DECL(name)
@@ -389,19 +389,19 @@ STM32_UART_IRQ_HANDLER_DECL(name);					\
 									\
 static const struct uart_stm32_config uart_stm32_cfg_##name = {		\
 	.uconf = {							\
-		.base = (u8_t *)CONFIG_UART_STM32_##name##_BASE_ADDRESS,\
+		.base = (u8_t *)DT_UART_STM32_##name##_BASE_ADDRESS,\
 		STM32_UART_IRQ_HANDLER_FUNC(name)			\
 	},								\
-	.pclken = { .bus = CONFIG_UART_STM32_##name##_CLOCK_BUS,	\
-		    .enr = CONFIG_UART_STM32_##name##_CLOCK_BITS	\
+	.pclken = { .bus = DT_UART_STM32_##name##_CLOCK_BUS,	\
+		    .enr = DT_UART_STM32_##name##_CLOCK_BITS	\
 	},								\
-	.baud_rate = CONFIG_UART_STM32_##name##_BAUD_RATE		\
+	.baud_rate = DT_UART_STM32_##name##_BAUD_RATE		\
 };									\
 									\
 static struct uart_stm32_data uart_stm32_data_##name = {		\
 };									\
 									\
-DEVICE_AND_API_INIT(uart_stm32_##name, CONFIG_UART_STM32_##name##_NAME,	\
+DEVICE_AND_API_INIT(uart_stm32_##name, DT_UART_STM32_##name##_NAME,	\
 		    &uart_stm32_init,					\
 		    &uart_stm32_data_##name, &uart_stm32_cfg_##name,	\
 		    PRE_KERNEL_1, CONFIG_KERNEL_INIT_PRIORITY_DEVICE,	\