[HUST-CSE]Add null pointer check in OSA_TaskSetPriority

[cospine]

1.这个PR修复的是什么问题？

源码 ： if (ptaskStruct->priority > tcb->priority)
这段代码在while循环未进入时，tcb易产生空指针问题
此处给出文件路径：
platform/vendor_bsp/nxp/MIMXRT1052/components/osa/fsl_os_abstraction_bm.c

2.这个PR不修复具体会带来什么后果？

tcb->priority无效，并会导致指针错误、程序崩溃

3.PR修复方案的依据是什么？

在原判断条件的基础上，添加对于空指针的检验，保证了代码的安全性：
if ((NULL == tcb) || (ptaskStruct->priority > tcb->priority))

4. 在什么环境下测试或者验证过？

all

[tencent-adm]

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