packagegroup-qt5-toolchain-target/qttranslations: fix nothing provides qttranslations-qtconfig

It failed to build meta-toolchain-qt5:
...
Error:
 Problem: conflicting requests
  - nothing provides qttranslations-qtconfig needed by packagegroup-qt5-toolchain-target-1.0-r0.noarch
...

The upstream removed qtconfig translations:
...
commit a6b3446cb023e7b3a5f8aa12ea0d650d2b804334
Author: Alexander Volkov <a.volkov@rusbitech.ru>
Date:   Thu Sep 14 19:33:25 2017 +0300

    Remove qtconfig translations
...

Signed-off-by: Hongxu Jia <hongxu.jia@windriver.com>

recipes-qt/packagegroups/packagegroup-qt5-toolchain-target.bb

@@ -45,7 +45,6 @@ RDEPENDS_${PN} += " \
     qtbase-staticdev \
     qttranslations-qt \
     qttranslations-qtbase \
-    qttranslations-qtconfig \
     qttranslations-qthelp \
     qtcharts-dev \
     qtcharts-mkspecs \

recipes-qt/qt5/qttranslations_git.bb

@@ -22,7 +22,6 @@ PACKAGES =. " \
     ${PN}-qtwebsockets \
     ${PN}-qtwebengine \
     ${PN}-qtxmlpatterns \
-    ${PN}-qtconfig \
     ${PN}-qtquick1 \
     ${PN}-qtscript \
     ${PN}-qtserialport \
@@ -83,10 +82,6 @@ FILES_${PN}-qtxmlpatterns = " \
     ${OE_QMAKE_PATH_TRANSLATIONS}/qtxmlpatterns_*.qm \
 "
 
-FILES_${PN}-qtconfig = " \
-    ${OE_QMAKE_PATH_TRANSLATIONS}/qtconfig_*.qm \
-"
-
 FILES_${PN}-qtquick1 = " \
     ${OE_QMAKE_PATH_TRANSLATIONS}/qtquick1_*.qm \
 "