mips: Move initrd_start check after initrd address sanitisation.

stable inclusion
from stable-v5.10.185
commit d47b5a6d233196ccbdc6791e99d6a70cc2938968
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8L5XP

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=d47b5a6d233196ccbdc6791e99d6a70cc2938968



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[ Upstream commit 4897a898 ]

PAGE_OFFSET is technically a virtual address so when checking the value of
initrd_start against it we should make sure that it has been sanitised from
the values passed by the bootloader. Without this change, even with a bootloader
that passes correct addresses for an initrd, we are failing to load it on MT7621
boards, for example.

Signed-off-by: Liviu Dudau <liviu@dudau.co.uk>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>