EGL: Fix over zealous colorspace implementation

Was processing HDR metadata attributes at CreateSurface time
and that's not what's in the spec. Removed it.

Update comments to clarify what's happening.

Be sure to check for colorspace extension support.

Test: adb -d shell am start -n \
      com.drawelements.deqp/android.app.NativeActivity \
      -e cmdLine '"deqp --deqp-case=dEQP-EGL.functional.wide_color.* \
      --deqp-log-filename=/sdcard/dEQP-Log.qpa"'
Test: adb -d shell am start -n \
      com.drawelements.deqp/android.app.NativeActivity \
      -e cmdLine '"deqp --deqp-case=dEQP-EGL.functional.hdr_metadata.* \
      --deqp-log-filename=/sdcard/dEQP-Log.qpa"'
Bug: 72828483

Change-Id: I2b89dce1f9c78331ea6cd550c4dda5893dd3ee7e