Callee saved registers do not include the LR anymore, so we can
now remove the last place where we pass a non-default template
argument to PushCPURegList/PopCPURegList (in the code generator).
This makes the template argument redundant, so we can remove the
template altogether.

Change-Id: I07f0c0a10840817df8a5afc1dc74330e290ce5bf
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3571816Reviewed-by: Jakob Linke <jgruber@chromium.org>
Commit-Queue: Georgia Kouveli <georgia.kouveli@arm.com>
Cr-Commit-Position: refs/heads/main@{#79842}