i965: Allocate tile aligned height

i965: Allocate tile aligned height

This patch shouldn't actually do anything because the libdrm function
should already do this alignment. However, it preps us for a future
patch where we add in the CCS AUX size, and in the process it serves as
a good place to find bisectable issues if libdrm or kernel does
something incorrectly.

v2: Do proper alignment for X tiling, and make sure non-tiled case is
handled (Jason)
v3: Rebase (Daniel)

Reviewed-by: Daniel Stone <daniels@collabora.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>