Remove EGL context limit for Adreno GPUs.

This change allows Adreno GPUs to have multiple EGL contexts. We had
to limit this in earlier versions of Android due to limitations in
the Adreno GPU driver (only 8 EGL contexts allowed system wide.)
That brand of GPU has improved its EGL drivers to support multiple
EGL contexts in more recent versions of their drivers used on more
recent versions of Android.

Bug: 6142005
Change-Id: Id3030466be9a3d9fbe728f1785378c1f05da98fe