sdl_sound: refactor *_CONF_OPT assignment with cpu-feature options

Signed-off-by: Samuel Martin <s.martin49@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/sdl_sound/sdl_sound.mk

@@ -32,8 +32,7 @@ SDL_SOUND_CONF_OPT = \
 	--disable-sdltest \
 	--enable-static
 
-# enable mmx for newer x86's
-ifeq ($(BR2_i386)$(BR2_x86_i386)$(BR2_x86_i486)$(BR2_x86_i586)$(BR2_x86_pentiumpro)$(BR2_x86_geode),y)
+ifeq ($(BR2_X86_CPU_HAS_MMX),y)
 SDL_SOUND_CONF_OPT += --enable-mmx
 else
 SDL_SOUND_CONF_OPT += --disable-mmx