reason:
up_set_current_regs initially had two functions:
1: To mark the entry into an interrupt state.
2: To record the context before an interrupt/exception. If we switch to
a new task, we need to store the upcoming context regs by calling up_set_current_regs(regs).
Currently, we record the context in other ways, so the second function is obsolete. Therefore,
we need to rename up_set_current_regs to better reflect its actual meaning, which is solely to mark an interrupt.
Signed-off-by: hujun5 <hujun5@xiaomi.com>