x86: Increase exception stack sizes

x86: Increase exception stack sizes

BugLink: https://bugs.launchpad.net/bugs/1951822
[ Upstream commit 7fae4c24a2b84a66c7be399727aca11e7a888462 ]

It turns out that a single page of stack is trivial to overflow with
all the tracing gunk enabled. Raise the exception stacks to 2 pages,
which is still half the interrupt stacks, which are at 4 pages.

Reported-by: Michael Wang <yun.wang@linux.alibaba.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/YUIO9Ye98S5Eb68w@hirez.programming.kicks-ass.net
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>