[fix][libcpu][riscv][t-head] fix rt_hw_interrupt_disable/rt_hw_interrupt_enable bug

使用不同的优化等级会出现不同的效果
当使用-O0 等级时，无法正确得到关闭中断之前的状态

Using different optimization levels will have different effects
When the - o0 level is used, the state before the shutdown interrupt cannot be obtained correctly

libcpu/risc-v/t-head/e9xx/context_gcc.S

@@ -45,12 +45,12 @@ rt_hw_context_switch_to:
     /* save a0 to to_thread */
     la      t0, rt_interrupt_to_thread
     STORE   a0, (t0)
-    
+
     /* save 0 to from_thread */
     la      t0, rt_interrupt_from_thread
     li      t1, 0
     STORE   t1, (t0)
-    
+
     /* set rt_thread_switch_interrupt_flag=1 */
     la      t0, rt_thread_switch_interrupt_flag
     li      t1, 1
@@ -97,7 +97,7 @@ rt_hw_context_switch_interrupt:
     beq     t1, t2, .reswitch
     /*  set rt_thread_switch_interrupt_flag=1 */
     STORE   t2, (t0)
-  
+
     /* update from_thread */
     la      t0, rt_interrupt_from_thread
     STORE   a0, (t0)
@@ -137,7 +137,7 @@ PendSV_Handler:
     la      t0, rt_interrupt_from_thread
     lw      t1, (t0)
     beqz    t1, .switch_to_thead
-    
+
     /* restore from thread context t0,t1 */
     lw      t0, (-4)(sp)
     lw      t1, (-8)(sp)
@@ -328,6 +328,23 @@ PendSV_Handler:
 
 .pendsv_exit:
     mret
- 
+
+/*
+ * rt_base_t rt_hw_interrupt_disable(void);
+ */
+    .globl rt_hw_interrupt_disable
+    .type   rt_hw_interrupt_disable, %function
+rt_hw_interrupt_disable:
+    csrrci a0, mstatus, 8
+    ret
 
 
+/*
+ * void rt_hw_interrupt_enable(rt_base_t level);
+ */
+    .globl rt_hw_interrupt_enable
+    .type   rt_hw_interrupt_enable, %function
+rt_hw_interrupt_enable:
+    csrw mstatus, a0
+    ret
+

libcpu/risc-v/t-head/e9xx/cpuport.c

@@ -134,34 +134,6 @@ rt_uint8_t *rt_hw_stack_init(void       *tentry,
     return stk;
 }
 
-
-/**
- * This function will disable global interrupt
- *
- * @param none
- *
- * @return zero
- */
-
-rt_base_t rt_hw_interrupt_disable(void)
-{
-    __asm volatile("csrrci a0, mstatus, 8");
-    return;
-}
-
-/**
- * This function will ennable global interrupt
- *
- * @param level not used
- *
- * @return none
- */
-/* XXX:rename rt_hw_interrupt_restore? */
-void rt_hw_interrupt_enable(rt_base_t level)
-{
-    __asm volatile("csrw mstatus, a0");
-}
-
 /** shutdown CPU */
 RT_WEAK void rt_hw_cpu_shutdown()
 {