Revert "x86: UV: raw_spinlock conversion"

[ Upstream commit 2a9c45d8f89112458364285cbe2b0729561953f1 ]

Drop the Ultraviolet patch. UV looks broken upstream for PREEMPT, too.
Mike is the only person I know that has such a thing and he isn't going
to fix this upstream (from 1526977462.6491.1.camel@gmx.de):

|From: Mike Galbraith <gleep@gmx.de>
|On Tue, 2018-05-22 at 08:50 +0200, Sebastian Andrzej Siewior wrote:
|>
|> Regarding the preempt_disable() in the original patch in uv_read_rtc():
|> This looks essential for PREEMPT configs. Is it possible to get this
|> tested by someone or else get rid of the UV code? It looks broken for
|> "uv_get_min_hub_revision_id() != 1".
|
|I suspect SGI cares not one whit about PREEMPT.
|
|> Why does PREEMPT_RT require migrate_disable() but PREEMPT only is fine
|> as-is? This does not look right.
|
|UV is not ok with a PREEMPT config, it's just that for RT it's dirt
|simple to shut it up, whereas for PREEMPT, preempt_disable() across
|uv_bau_init() doesn't cut it due to allocations, and whatever else I
|would have met before ending the whack-a-mole game.
|
|If I were in your shoes, I think I'd just stop caring about UV until a
|real user appears.  AFAIK, I'm the only guy who ever ran RT on UV, and
|I only did so because SUSE asked me to look into it.. years ago now.
|
|        -Mike

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>