Add alignment for the direct mode handler (#449)

It is still possible to further relax the alignment using linker script
if needed.

Signed-off-by: Gaurav Aggarwal <aggarg@amazon.com>

portable/GCC/RISC-V/portASM.S

@@ -320,6 +320,7 @@ exit_without_context_switch:
 /*-----------------------------------------------------------*/
 
 .section .text.freertos_risc_v_trap_handler
+.align 8
 freertos_risc_v_trap_handler:
     portcontextSAVE_CONTEXT_INTERNAL