runtime: fix inline assembly trampoline for arm64
runtime: fix inline assembly trampoline for arm64

Use the program counter to compute the address of the first instruction
of the ret sled. The ret sled is located after 5 instructions from the
MOVD instruction saving the value of the program counter.

Change-Id: Ie7ae7a0807785d6fea035cf7a770dba7f37de0ec
GitHub-Last-Rev: 2719208c6a3b049e0f394e5311ce3282b58f8516
GitHub-Pull-Request: golang/go#53039
Reviewed-on: https://go-review.googlesource.com/c/go/+/407895
Reviewed-by: Cherry Mui <d62e63aa42ce272d7b6a5055d97e942b33a34679@google.com>
Reviewed-by: Alan Donovan <7069e9552f9d110b0a0f326b96f22f63fb99dfc1@google.com>

nawawi/go,nawawi/go,nawawi/go,golang/go,golang/go,nawawi/go,golang/go,nawawi/go,nawawi/go,golang/go,golang/go,golang/go,nawawi/go,golang/go,golang/go,nawawi/go