LoongArch: Remove unnecessary checks for ORC unwinder

According to the following function definitions, __kernel_text_address()
already checks __module_text_address(), so it should remove the check of
__module_text_address() in bt_address() at least.

int __kernel_text_address(unsigned long addr)
{
if (kernel_text_address(addr))
return 1;
...
return 0;
}

int kernel_text_address(unsigned long addr)
{
bool no_rcu;
int ret = 1;
...
if (is_module_text_address(addr))
goto out;
...
return ret;
}

bool is_module_text_address(unsigned long addr)
{
guard(rcu)();
return __module_text_address(addr) != NULL;
}

Furthermore, there are two checks of __kernel_text_address(), one is in
bt_address() and the other is after calling bt_address(), it looks like
redundant.

Handle the exception address first and then use __kernel_text_address()
to validate the calculated address for exception or the normal address
in bt_address(), then it can remove the check of __kernel_text_address()
after calling bt_address().

Just remove unnecessary checks, no functional changes intended.

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>