glmemory: normalize the internal format we pass into glTex* functions

Passing unsized formats sometimes breaks on embedded platforms

Take 2 at 694e30f8,
gstreamer/gst-plugins-base!49
7 jobs for android-gl-yuv2 in 79 minutes and 9 seconds (queued for 5 minutes and 39 seconds)
Status Job ID Name Coverage
  Preparation
passed #61712
gst indent

00:00:31

passed #61711
manifest

00:00:22

 
  Build
passed #61713
build fedora x86_64

00:03:21

 
  Test
passed #61714
check fedora

00:16:15

 
  Full Builds
passed #61715
build android arm64 api28

00:02:56

passed #61803
build cerbero fedora x86_64

00:55:42

failed #61716
build cerbero fedora x86_64

01:17:19