package/pipewire: fix webrtc-audio-processing condition

The condition checking whether the webrtc-audio-processing package is
enabled, added in commit
3ccd3b4c384e98703841b12f7309362957f8f17d ("package/pipewire: bump to
version 0.3.32") is obviously incorrect, and can never be true.

Fix the condition to use the correct variable instead.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
(cherry picked from commit 52f8db409fade387f0f90940c0b32acb27317017)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/pipewire/pipewire.mk

@@ -216,7 +216,7 @@ else
 PIPEWIRE_CONF_OPTS += -Dcompress-offload=disabled
 endif
 
-ifeq ($(WEBRTC_AUDIO_PROCESSING),y)
+ifeq ($(BR2_PACKAGE_WEBRTC_AUDIO_PROCESSING),y)
 PIPEWIRE_CONF_OPTS += -Decho-cancel-webrtc=enabled
 PIPEWIRE_DEPENDENCIES += webrtc-audio-processing
 else