Revert "add brcm2708-bcm2710 for raspi 4 support"

This reverts commit 0df9f251. The target
doesn't seem to be supported, the build failed:

  make[1]: Leaving directory '/builds/firmware/site-ffs/gluon/openwrt'
  Please set GLUON_TARGET to a valid target. Gluon supports the following targets:
   * ar71xx-generic
   * ar71xx-tiny
   * ar71xx-nand
   * ath79-generic
   * brcm2708-bcm2708
   * brcm2708-bcm2709
   * ipq40xx-generic
   * ipq806x-generic
   * lantiq-xrx200
   * lantiq-xway
   * mpc85xx-generic
   * mpc85xx-p1020
   * ramips-mt7620
   * ramips-mt7621
   * ramips-mt76x8
   * ramips-rt305x
   * sunxi-cortexa7
   * x86-generic
   * x86-geode
   * x86-legacy
   * x86-64
  Makefile:158: recipe for target 'config' failed

.gitlab-ci.yml

@@ -91,11 +91,6 @@ target:brcm2708-bcm2709:
   variables:
     GLUON_TARGET: brcm2708-bcm2709
  
-target:brcm2708-bcm2710:
-  extends: .target
-  variables:
-    GLUON_TARGET: brcm2708-bcm2710
- 
 target:ipq40xx-generic:
   extends: .target
   variables:

buildall.sh

@@ -12,7 +12,6 @@ TARGETS=(
     ath79-generic
     brcm2708-bcm2708
     brcm2708-bcm2709
-    brcm2708-bcm2710
     ipq40xx-generic
     ipq806x-generic
     lantiq-xrx200