egl: Fallback if a driver doesn't support egl 1.5

Some drivers may claim to support egl 1.5, but don't actually
expose all the APIs necessary for conformance.

Instead of erroring out when attempting to use this functionality,
which can prevent doing anything useful with the driver, proactively
check for the APIs and downgrade to egl 1.4 if they're not present.

Bug: 128446160
Test: dEQP on Marlin
Change-Id: Ief082ff018876ae38bfe86b64a23d29ff2ce0d4b