Revert "arm64/alternatives: use subsections for replacement sequences"

This reverts commit a8f13826 which is
commit f7b93d42 upstream as it causes
clang to go boom.

Cc: Will Deacon <willdeacon@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I082c05e3d9cc00fd7173897a7c89c56aecf7facb