build: generate x86's asm-macros.h with filechk

build: generate x86's asm-macros.h with filechk

When we will build out-of-tree, make is going to try to generate
"asm-macros.h" before the directories "arch/x86/include/asm" exist,
thus we would need to call `mkdir` explicitly. We will use "filechk"
for that as it does everything that the current recipe does and does
call `mkdir`.

Also, they are no more "*.new" files generated in this directory.

Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>