intel/isl: Add a unit suffixes to some struct fields and variables

intel/isl: Add a unit suffixes to some struct fields and variables

I was about to make the claim to someone that every field in isl_surf
is either an enum or has explicit units.  Then I looked at isl_surf and
discovered this claim was wrong.  We should fix that.  This commit does
a few refactors:

 * Add _B suffixes to some struct fields
 * Add _B to some variables and parameters
 * Rename row_pitch_tiles -> row_pitch_tl

Reviewed-by: Nanley Chery <nanley.g.chery@intel.com>