automake: drop "EGL_" from HAVE_EGL_PLATFORM_WAYLAND

Analogous to previous commit.

Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
diff --git a/src/Makefile.am b/src/Makefile.am
index 9a1fddf..29d4ea9 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -38,7 +38,7 @@
 SUBDIRS += glx
 endif
 
-if HAVE_EGL_PLATFORM_WAYLAND
+if HAVE_PLATFORM_WAYLAND
 SUBDIRS += egl/wayland/wayland-egl egl/wayland/wayland-drm
 endif