egl: Overhaul driver API.

egl: Overhaul driver API.

The motivation is so that drivers do not need to look up and check for
bad display, context, and etc.  It also becomes unnecessary for drivers
to call the link functions.

This commit makes eglapi.[ch] do the lookup and check.  As a result, the
driver API is overhauled, and almost all sources and drivers need
update.  The updates are mainly find and replace with human brains.

Signed-off-by: Chia-I Wu <olvaffe@gmail.com>