Use (32-bit) word-sized access in the a4x bus space routine even if only

Use (32-bit) word-sized access in the a4x bus space routine even if only
a byte or a half-word is needed.  Certain implementations of the Synopsis
Designware copy-and-paste logic blocks don't respond to transactions that
are smaller than a word.

Fixes the serial console on boards with a Rockchip RK3288.