asus-grouper: add mdss-fb-init-hack (!170)

mdss-fb-init-hack fixes the black screen (e.g. in XFCE4)

device/device-asus-grouper/APKBUILD

 pkgname=device-asus-grouper
 pkgver=1
-pkgrel=15
+pkgrel=16
 pkgdesc="Asus Nexus 7 2012 Wifi"
 url="https://postmarketos.org"
 arch="armhf"
 license="MIT"
-depends="postmarketos-base linux-asus-grouper mkbootimg mesa-dri-swrast"
+depends="postmarketos-base linux-asus-grouper mkbootimg mesa-dri-swrast mdss-fb-init-hack"
 makedepends=""
 install=""
 subpackages=""