ftrace: Store the order of pages allocated in ftrace_page

mainline inclusion
from mainline-v5.13-rc1
commit db42523b
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7KYPM

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=db42523b4f3e83ff86b53cdda219a9767c8b047f

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Instead of saving the size of the records field of the ftrace_page, store
the order it uses to allocate the pages, as that is what is needed to know
in order to free the pages. This simplifies the code.

Link: https://lore.kernel.org/lkml/CAHk-=whyMxheOqXAORt9a7JK9gc9eHTgCJ55Pgs4p=X3RrQubQ@mail.gmail.com/



Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[ change log written by Steven Rostedt ]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>