添加bootload相关代码，以及配置。支持pwm在bootload开启

bootloader/flashboot_ws63/startup/riscv_init.S

@@ -0,0 +1,93 @@
+/*
+ * Copyright (c) HiSilicon (Shanghai) Technologies Co., Ltd. 2021-2021. All rights reserved.
+ * Description: main
+ *
+ * Create: 2021-03-09
+ */
+
+        .section .text.entry
+        .global _start
+        .option norvc
+_start:
+        j Reset_Handler
+
+Reset_Handler:
+        li t0,0x0
+        csrw pmpcfg0,t0
+        li t0,0x0
+        csrw pmpcfg1,t0
+        li t0,0x0
+        csrw pmpcfg2,t0
+        li t0,0x0
+        csrw pmpcfg3,t0
+        li t0,0x0
+        csrw 0x7d9,t0
+        la t0, __flash_boot_flag_begin__
+        mv t1, a0
+        lw     t3, (t1)
+        sw     t3, (t0)
+        la t0, trap_vector
+        addi t0, t0, 1
+        csrw mtvec, t0
+        csrwi mstatus, 0
+        csrwi mie, 0
+
+        # initialize global pointer
+        la gp, _gp_
+
+        # initialize stack pointer
+        la sp, __stack_top__
+
+        /* init stack */
+        la      t0, g_system_stack_begin
+        la      t1, g_system_stack_end
+        beq     t0, t1, end_set_stack_loop
+        li      t2, 0xefbeadde
+
+set_stack_loop:
+        sw      t2, (t0)
+        addi    t0, t0, 4
+        blt     t0, t1, set_stack_loop
+end_set_stack_loop:
+
+        /* clear reg */
+        li      ra, 0
+        li      tp, 0
+        li      s0, 0
+        li      s1, 0
+        li      a0, 0
+        li      a1, 0
+        li      a2, 0
+        li      a3, 0
+        li      a4, 0
+        li      a5, 0
+        li      a6, 0
+        li      a7, 0
+        li      s2, 0
+        li      s3, 0
+        li      s4, 0
+        li      s5, 0
+        li      s6, 0
+        li      s7, 0
+        li      s8, 0
+        li      s9, 0
+        li      s10, 0
+        li      s11, 0
+        li      t3, 0
+        li      t4, 0
+        li      t5, 0
+        li      t6, 0
+
+        /* clear bss section */
+        la      t0, __bss_begin__
+        la      t1, __bss_end__
+        beq     t0, t1, end_clear_bss_loop
+        li      t2, 0x00000000
+
+clear_bss_loop:
+        sw      t2, (t0)
+        addi    t0, t0, 4
+        blt     t0, t1, clear_bss_loop
+end_clear_bss_loop:
+
+        j       start_fastboot