kmscube: Remove the manually creation of m4 directory

Since kmscube upstream commit a2dc60cf05b704 ("Add m4/.gitignore")
there is no need to manually create the m4 directory anymore, so
simply remove KMSCUBE_POST_PATCH_HOOKS.

Signed-off-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/kmscube/kmscube.mk

@@ -10,10 +10,4 @@ KMSCUBE_LICENSE = MIT
 KMSCUBE_DEPENDENCIES = host-pkgconf mesa3d libdrm
 KMSCUBE_AUTORECONF = YES
 
-# Autoreconf requires an existing m4 directory
-define KMSCUBE_PATCH_M4
-	mkdir -p $(@D)/m4
-endef
-KMSCUBE_POST_PATCH_HOOKS += KMSCUBE_PATCH_M4
-
 $(eval $(autotools-package))