Provide replacements for iowrite32be and ioread32be if needed

Provide replacements for iowrite32be and ioread32be if needed

The architectures that don't set CONFIG_GENERIC_IOMAP are supposed to
provide replacements for functions in lib/iomap.c, but not all provide
iowrite32be() and ioread32be().

Only MIPS, PARISC and PowerPC implement iowrite32be and ioread32be as
functions, while SH and AVR32 provide macros.  Other architectures, in
particular ARM, provide no replacement at all.

This should fix ticket #1539.

git-svn-id: http://madwifi-project.org/svn/madwifi/trunk@2932 0192ed92-7a03-0410-a25b-9323aeb14dbd