Revert "mm: kmemleak: take a full lowmem check in kmemleak_*_phys()"

stable inclusion
from stable-v4.19.258
commit aabdbd63c46ff6fa6661dd9d3aaaebb62141db90
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5UQH4
CVE: NA

--------------------------------

This reverts commit 23c2d497de21f25898fbea70aeb292ab8acc8c94.

Commit 23c2d497de21 ("mm: kmemleak: take a full lowmem check in
kmemleak_*_phys()") brought false leak alarms on some archs like arm64
that does not init pfn boundary in early booting. The final solution
lands on linux-6.0: commit 0c24e061196c ("mm: kmemleak: add rbtree and
store physical address for objects allocated with PA").

Revert this commit before linux-6.0. The original issue of invalid PA
can be mitigated by additional check in devicetree.

The false alarm report is as following: Kmemleak output: (Qemu/arm64)
unreferenced object 0xffff0000c0170a00 (size 128):
  comm "swapper/0", pid 1, jiffies 4294892404 (age 126.208s)
  hex dump (first 32 bytes):
 62 61 73 65 00 ...