x86: Use enum instead of literals for trap values

x86: Use enum instead of literals for trap values

commit c94082656dac74257f63e91f78d5d458ac781fa5 upstream.

The traps are referred to by their numbers and it can be difficult to
understand them while reading the code without context. This patch adds
enumeration of the trap numbers and replaces the numbers with the correct
enum for x86.

Signed-off-by: Kees Cook <keescook@chromium.org>
Link: http://lkml.kernel.org/r/20120310000710.GA32667@www.outflux.net
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cherry-picked-for: v2.3.37
Signed-off-by: John Kacur <jkacur@redhat.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>