Only use the first available suffix value when loading drivers.

Change the EGL loader to use only the first available suffix value when
loading the GLES drivers. Previously the loader will continue to read
values from a list of properties if it fails to load the value from the
previous property.  However, this silent fallback should not have
happened, the value of the driver suffix properties must be set
correctly or left empty if it's not intended to be used.

Bug: b/277100371
Test: boot with persist.graphics.egl points to a nonexisted drivers
Change-Id: Id6dd9a5aec5e737e8251f9b5f63176a9f8ebc594