Boot sequence PANIC when setting SPI6 to NS in TF-A device tree

[cfilipescu]

When trying to migrate a project (STM32MP153A) from basic uboot (Ecosystem 1.3) config to trusted (Ecosystem 2.1) system panics when booting TF-A because of SPI6 being enabled and assigned to the nonsecure core.

Is this expected behaviour or just a regression?

NOTICE:  CPU: STM32MP153AAC Rev.B
NOTICE:  Model: STMicroelectronics custom STM32CubeMX board
INFO:    Reset reason (0x15):
INFO:      Power-on Reset (rst_por)
INFO:    PMIC version = 0x21
INFO:    Using SDMMC
INFO:      Instance 1
INFO:    Boot used partition fsbl1
NOTICE:  BL2: v2.2-r2.0(debug):2020.08-rc1-3282-g35ea9648ac-dirty
NOTICE:  BL2: Built : 09:37:37, Mar  3 2021
INFO:    Using crypto library 'stm32_crypto_lib'
INFO:    BL2: Doing platform setup
INFO:    RAM: DDR3-DDR3L 16bits 533000Khz
INFO:    Memory size = 0x20000000 (512 MB)
INFO:    BL2 runs SP_MIN setup
INFO:    BL2: Loading image id 4
INFO:    Loading image id=4 at address 0x2ffeb000
INFO:    Image id=4 loaded: 0x2ffeb000 - 0x2ffff000
INFO:    BL2: Loading image id 5
INFO:    Loading image id=5 at address 0xc0100000
INFO:    STM32 Image size : 886941
INFO:    Image id=5 loaded: 0xc0100000 - 0xc01d889d
WARNING: Skip signature check (header option)
NOTICE:  ROTPK is not deployed on platform. Skipping ROTPK verification.
NOTICE:  BL2: Booting BL32
INFO:    Entry point address = 0x2ffeb000
INFO:    SPSR = 0x1d3
Lr0L
    ;>
      8B<¼<rLL@626r82>2NNrN

&etzpc {
	st,decprot = <
		DECPROT(STM32MP1_ETZPC_SPI6_ID, DECPROT_NS_RW, DECPROT_UNLOCK)
	>;
};