[EFL] Clean up and refactor the memory cache functions in ewk_settings.

[EFL] Clean up and refactor the memory cache functions in ewk_settings.
https://bugs.webkit.org/show_bug.cgi?id=72140

Reviewed by Antonio Gomes.

Use a better naming prefix, as "ewk_settings_cache" was too general,
and make it possible to pass all parameters to
MemoryCache::setCapacities().

* ewk/ewk_settings.cpp:
(ewk_settings_object_cache_capacity_set):
(ewk_settings_object_cache_enable_get):
(ewk_settings_object_cache_enable_set):
* ewk/ewk_settings.h:

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@102971 268f45cc-cd09-0410-ab3c-d52691b4dbfc