staging: unisys/visorbus: add __init/__exit annotations

gcc-4.6 causes a harmless warning about the init function:

WARNING: vmlinux.o(.text+0xed62c2): Section mismatch in reference from the function init_unisys() to the function .init.text:visorutil_spar_detect()
The function init_unisys() references
the function __init visorutil_spar_detect().
This is often because init_unisys lacks a __init
annotation or the annotation of visorutil_spar_detect is wrong.

It appears that newer versions inline visorutil_spar_detect(),
end up with an empty __init section. This marks the module
entry points as __init and __exit respectively, which avoids
the warning and slightly reduces the runtime code size.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>