plat/stm32mp1: fdt helpers for secure aware gpio bank

New helper functions to get GPIO banks configuration from the FDT.

stm32_get_gpio_bank_pinctrl_node() allows stm32mp platforms to
differentiate specific GPIO banks when these are defined with a specific
path in the FDT.

fdt_get_gpio_bank_pin_count() returns the number of pins in a GPIO bank
as it depends on the SoC variant.

Change-Id: I4481774152b3c6bf35bf986f58e357c2f9c19176
Signed-off-by: Etienne Carriere <etienne.carriere@st.com>
diff --git a/plat/st/common/include/stm32mp_common.h b/plat/st/common/include/stm32mp_common.h
index 27ddab0..feeb4a7 100644
--- a/plat/st/common/include/stm32mp_common.h
+++ b/plat/st/common/include/stm32mp_common.h
@@ -61,6 +61,9 @@
 unsigned long stm32_get_gpio_bank_clock(unsigned int bank);
 uint32_t stm32_get_gpio_bank_offset(unsigned int bank);
 
+/* Return node offset for target GPIO bank ID @bank or a FDT error code */
+int stm32_get_gpio_bank_pinctrl_node(void *fdt, unsigned int bank);
+
 /* Print CPU information */
 void stm32mp_print_cpuinfo(void);