lib: sbi: Fix how to check whether the domain contains fw_region

Because firmware is split into rw/rx segments, it cannot be recorded
by a root_fw_region. This problem is solved by adding a flag
fw_region_inited to sbi_domain.

Signed-off-by: Xiang W <wxjstz@126.com>
Reviewed-by: Himanshu Chauhan <hchauhan@ventanamicro.com>
Reviewed-by: Anup Patel <anup@brainfault.org>

include/sbi/sbi_domain.h

@@ -122,6 +122,8 @@ struct sbi_domain {
 	bool system_reset_allowed;
 	/** Is domain allowed to suspend the system */
 	bool system_suspend_allowed;
+	/** Identifies whether to include the firmware region */
+	bool fw_region_inited;
 };
 
 /** The root domain instance */