ffmpeg: typo fix

Add missing bracket.

Signed-off-by: Karoly Kasza <kaszak@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/ffmpeg/ffmpeg.mk

@@ -342,7 +342,7 @@ FFMPEG_CONF_OPTS += $(call qstrip,$(BR2_PACKAGE_FFMPEG_EXTRACONF))
 
 ifneq ($(call qstrip,$(BR2_GCC_TARGET_CPU)),)
 FFMPEG_CONF_OPTS += --cpu=$(BR2_GCC_TARGET_CPU)
-else ifneq ($(call qstrip,$(BR2_GCC_TARGET_ARCH),)
+else ifneq ($(call qstrip,$(BR2_GCC_TARGET_ARCH)),)
 FFMPEG_CONF_OPTS += --cpu=$(BR2_GCC_TARGET_ARCH)
 endif