[PATCH] zd1211rw: Remove addressing abstraction

Instead of passing our own custom 32-bit addresses around and
translating them, this patch makes all our register address constants
absolute and removes the translation.

There are two ugly parts:
 - fw_reg_addr() is needed to compute addresses of firmware registers, as this
   is dynamic based upon firmware
 - inc_addr() needs a small hack to handle byte vs word addressing

However, both of those are only small, and we don't use fw_regs a whole
lot anyway.

The bonuses here include simplicity and improved driver readability. Also, the
fact that registers are now referenced by 16-bit absolute addresses (as
opposed to 32-bit pseudo addresses) means that over 2kb compiled code size has
been shaved off.

Includes some touchups and sparse fixes from Ulrich Kunitz.

Signed-off-by: Daniel Drake <dsd@gentoo.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>