ipw2200, fix ipw io functions

- some of them are defined as follows:
  #define ipw_write32	expr1; expr2
  and are called from loops or ifs without a compound statement, so
  they are broken. Fix it by putting them into do {} while (0) for
  writes and ({ }) for reads.
- also unify and cleanup them while at it -- convert them from
  macros to inline functions, so that we get some basic typechecking

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Acked-by: Zhu Yi <yi.zhu@intel.com>
Cc: James Ketrenos <jketreno@linux.intel.com>
Cc: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>