detach risc-v kernel code from gd32v lib

arch/risc-v/common/tos_cpu.c

@@ -1,5 +1,4 @@
 #include <tos.h>
-#include <riscv_encoding.h>
 #include <riscv_port.h>
 
 __KERNEL__ void cpu_systick_init(k_cycle_t cycle_per_tick)
@@ -107,7 +106,7 @@ __KERNEL__ k_stack_t *cpu_task_stk_init(void *entry,
     regs->gp        = (cpu_data_t)gp;                           // gp: global pointer
     regs->a0        = (cpu_data_t)arg;                          // a0: argument
     regs->ra        = (cpu_data_t)0xACE00ACE;                   // ra: return address
-    regs->mstatus   = (cpu_data_t)(MSTATUS_MPP | MSTATUS_MPIE); // return to machine mode and enable interrupt
+    regs->mstatus   = (cpu_data_t)0x00001880;                   // return to machine mode and enable interrupt
     regs->epc       = (cpu_data_t)entry;
 
 

arch/risc-v/rv32i/gcc/port_c.c

@@ -1,5 +1,4 @@
 #include <tos.h>
-#include "riscv_encoding.h"
 #include "riscv_port.h"
 
 __PORT__ void port_systick_config(uint32_t cycle_per_tick)

arch/risc-v/rv32i/gcc/port_s.S

@@ -15,8 +15,14 @@
 .extern k_curr_task
 .extern k_next_task
 
+#define MSTATUS_MIE         0x00000008
+#define MSTATUS_MPP         0x00001800
 
-#include "riscv_encoding.h"
+#define MIE_MTIE            (1 << 7)
+
+#define MIP_MTIP            (1 << 7)
+
+#define REGBYTES            4
 
 .text
 .align 2
@@ -59,7 +65,6 @@ port_systick_pending_reset:
     csrc mip, t0
     ret
 
-#define REGBYTES 4
 
 .macro SAVE_CONTEXT
     addi   sp, sp, -32*REGBYTES