PPC/s390: [masm] Read builtin off builtin_entry_table rather than EmbeddedData...

Port c7949470

Original Commit Message:

    ... when we do have an isolate. This is a little leaner.

R=verwaest@chromium.org, joransiu@ca.ibm.com, junyan@redhat.com, midawson@redhat.com
BUG=
LOG=N

Change-Id: Ifd466b48f4f7a909d00fc32304f90ebd19e93110
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2965156


Reviewed-by: Junliang Yan <junyan@redhat.com>
Commit-Queue: Milad Fa <mfarazma@redhat.com>
Cr-Commit-Position: refs/heads/master@{#75192}