kbuild: Fix silent builds with make-4

make-4 changed the way/order it presents the command line options
into MAKEFLAGS

In make-3.8x, '-s' would always be first into a group of options
with the '-'/hyphen removed

$ make -p -s 2>/dev/null | grep ^MAKEFLAGS
MAKEFLAGS = sp

In make-4, '-s' seems to always be last into a group of options
with the '-'/hyphen removed

$ make -s -p 2>/dev/null | grep ^MAKEFLAGS
MAKEFLAGS = ps

Signed-off-by: Emil Medve <Emilian.Medve@Freescale.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>

Imported into device-tree.git, no changes required.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Merge branch 'build'