stm32mp15: remove configs dependency on CONFIG_TFABOOT

Remove the dependency on CONFIG_TFABOOT in stm32mp Kconfig
- always activate the ARCH config: CONFIG_ARCH_SUPPORT_PSCI
  and CONFIG_CPU_V7_HAS_NONSEC
- CONFIG_ARMV7_NONSEC is deactivated in trusted defconfig
- the correct sysreset driver is activated in each defconfig:
  CONFIG_SYSRESET_PSCI or SYSRESET_SYSCON

Reported-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>