objtool: Use arch_jump_destination() in read_intra_function_calls()

Use arch_jump_destiation() instead of the open-coded 'offset + len +
immediate' that is x86 specific.

Avoids future trouble with other architectures.

Signed-off-by: Chen Zhongjin <chenzhongjin@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20220818014553.220261-1-chenzhongjin@huawei.com