sbi: sbi_domain_context: Fix trap context for domain context switching

Save/restore sbi_trap_context during domain context switching to
ensure proper trap handling and isolation. This maintains correct
domain-specific state, avoiding context corruption.

Fixes: abea9497

 ("lib: sbi: Introduce trap context")
Signed-off-by: Yu Chien Peter Lin <peterlin@andestech.com>
Reviewed-by: Alvin Chang <alvinga@andestech.com>
Tested-by: Alvin Chang <alvinga@andestech.com>
Reviewed-by: Yong Li <yong.li@intel.com>
Tested-by: Yong Li <yong.li@intel.com>