x86: delete vsyscall files during make clean

make clean failed to delete a few files in
x86/kernel. This is because kbuild does not
see the correct/full kernel/Makefile.

As a workaround until the Makefiles are merged specify
the files to be deleted in the common Makefile.

Reported by Mike Galbraith <efault@gmx.de>

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

arch/x86/kernel/Makefile

@@ -3,3 +3,7 @@ include ${srctree}/arch/x86/kernel/Makefile_32
 else
 include ${srctree}/arch/x86/kernel/Makefile_64
 endif
+
+# Workaround to delete .lds files with make clean
+# The problem is that we do not enter Makefile_32 with make clean.
+clean-files := vsyscall*.lds vsyscall*.so