arm: imx: hab: Implement hab_rvt_failsafe

This patch implements the basic callback hooks for
hab_rvt_check_failsafe for BootROM code using the older BootROM address
layout - in my test case the i.MX7. Code based on new BootROM callbacks
will just do nothing and there's definitely a TODO to implement that extra
functionality on the alternative BootROM API.

Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Fabio Estevam <fabio.estevam@nxp.com>
Cc: Peng Fan <peng.fan@nxp.com>
Cc: Albert Aribaud <albert.u.boot@aribaud.net>
Cc: Sven Ebenfeld <sven.ebenfeld@gmail.com>
Cc: George McCollister <george.mccollister@gmail.com>
Cc: Breno Matheus Lima <brenomatheus@gmail.com>
Tested-by: Breno Lima <breno.lima@nxp.com>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>

arch/arm/mach-imx/hab.c

@@ -70,6 +70,21 @@
 	((hab_rvt_exit_t *)HAB_RVT_EXIT)			\
 )
 
+static inline void hab_rvt_failsafe_new(void)
+{
+}
+
+#define hab_rvt_failsafe_p				\
+(							\
+	(is_mx6dqp()) ?					\
+	((hab_rvt_failsafe_t *)hab_rvt_failsafe_new) :	\
+	(is_mx6dq() && (soc_rev() >= CHIP_REV_1_5)) ?	\
+	((hab_rvt_failsafe_t *)hab_rvt_failsafe_new) :	\
+	(is_mx6sdl() && (soc_rev() >= CHIP_REV_1_2)) ?	\
+	((hab_rvt_failsafe_t *)hab_rvt_failsafe_new) :	\
+	((hab_rvt_failsafe_t *)HAB_RVT_FAILSAFE)	\
+)
+
 static inline enum hab_status hab_rvt_check_target_new(enum hab_target target,
 						       const void *start,
 						       size_t bytes)