x86/oops: Show the correct CS value in show_regs()

show_regs() shows the CS in the CPU register instead of the value in
regs.  This means that we'll probably print "CS: 0010" almost all
the time regardless of what was actually in CS when the kernel
malfunctioned.  This gives a particularly confusing result if we
OOPSed due to an implicit supervisor access from user mode.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Link: http://lkml.kernel.org/r/4e36812b6e1e95236a812021d35cbf22746b5af6.1542841400.git.luto@kernel.org


Signed-off-by: Ingo Molnar <mingo@kernel.org>