drm/xe: Cleanup style warnings

Reduce the number of warnings reported by checkpatch.pl from 118 to 48 by
addressing those warnings types:

  LEADING_SPACE
  LINE_SPACING
  BRACES
  TRAILING_SEMICOLON
  CONSTANT_COMPARISON
  BLOCK_COMMENT_STYLE
  RETURN_VOID
  ONE_SEMICOLON
  SUSPECT_CODE_INDENT
  LINE_CONTINUATIONS
  UNNECESSARY_ELSE
  UNSPECIFIED_INT
  UNNECESSARY_INT
  MISORDERED_TYPE

Signed-off-by: Francois Dugast <francois.dugast@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>