Enable alpha quality support for new Intel hardware by default

configname: CONFIG_DRM_I915_ALPHA_SUPPORT

Linux Kernel Configuration
└─>Device Drivers
└─>Graphics support
└─>Enable alpha quality support for new Intel hardware by default
In linux kernel since version 4.1 (release Date: 2015-06-21)  
Choose this option if you have new Intel hardware and want to enable
the alpha quality i915 driver support for the hardware in this kernel
version. You can also enable the support at runtime using the module
parameter i915.alpha_support=1; this option changes the default for
that module parameter.

It is recommended to upgrade to a kernel version with proper support
as soon as it is available. Generally fixes for platforms with alpha
support are not backported to older kernels.

If in doubt, say "N".