hab: Change calling to ROM API failsafe

Modify to use hab_rvt_failsafe function for failsafe ROM API, not
directly call its ROM address. This function will wrap the sip call for iMX8M
platforms.

Signed-off-by: Ye Li <ye.li@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
diff --git a/arch/arm/mach-imx/hab.c b/arch/arm/mach-imx/hab.c
index f2d5f74..bd00d4a 100644
--- a/arch/arm/mach-imx/hab.c
+++ b/arch/arm/mach-imx/hab.c
@@ -539,14 +539,11 @@
 static int do_hab_failsafe(struct cmd_tbl *cmdtp, int flag, int argc,
 			   char *const argv[])
 {
-	hab_rvt_failsafe_t *hab_rvt_failsafe;
-
 	if (argc != 1) {
 		cmd_usage(cmdtp);
 		return 1;
 	}
 
-	hab_rvt_failsafe = (hab_rvt_failsafe_t *)HAB_RVT_FAILSAFE;
 	hab_rvt_failsafe();
 
 	return 0;