[Hardy] SRU: Fix boot panic on Acer Aspire One (v2)

[Stefan Bader]

SRU Justification:

Impact: Certain kernel versions cause a kernel panic on the Acer Aspire
One when the kernel changes its data to read-only pages. The underlying
problem is very timing sensitive (adding printks for debugging makes the
problem much less likely to occur).

Fix: As far as we understand, there might be another thread being
running (with a very speculative maybe related to freeing init memory)
which gets badly confused by the global_flush_tlb() (could also be
affected by the fact that changing the page attributes splits a large
kernel page). To prevent that we force all other CPUs to run the stop
work function, which basically acts like a  big sync. The performance
impact is minimal as this is done only once on boot. The change is
quirked to only happen on a Acer Aspire One.

Testcase: Booting testkernel on the Acer Aspire One and for comparison
on a Dell Inspiron 1521. Quirk gets activated and boot succeeds on the
Acer while the Dell goes through the same code as before.

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