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 Name Job ID Coverage
  Preparation
passed gst indent #61712

00:00:31

passed manifest #61711

00:00:22

 
  Build
passed build fedora x86_64 #61713

00:03:21

 
  Test
passed check fedora #61714

00:16:15

 
  Full Builds
passed build android arm64 api28 #61715

00:02:56

passed build cerbero fedora x86_64 #61803

00:55:42

failed build cerbero fedora x86_64 #61716

01:17:19