powerpc/ppc64: Remove the unneeded load of ti_flags in resume_kernel

We already got the value of current_thread_info and ti_flags and store
them into r9 and r4 respectively before jumping to resume_kernel. So
there is no reason to reload them again.

Signed-off-by: Kevin Hao <haokexin@gmail.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>