um/sysrq: remove needless variable sp

[ Upstream commit 3dd923f39a03dede001afe0edcc08613d5f403e5 ]

`sp' is a needless excercise here.

Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Link: http://lkml.kernel.org/r/20200418201944.482088-36-dima@arista.com


Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Stable-dep-of: 0f659ff362ea ("um: Always dump trace for specified task in show_stack")
Signed-off-by: Sasha Levin <sashal@kernel.org>