Canonicalize a few remaining header guards, with the exception for
those which are still in subarchitecture directories.
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>

Drop double underscores from header guards in arch/x86/include.  They
are used inconsistently, and are not necessary.
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>

Change header guards named "ASM_X86__*" to "_ASM_X86_*" since:

a. the double underscore is ugly and pointless.
b. no leading underscore violates namespace constraints.
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>