Staging: batman-adv: don't use default init_module/cleanup_module function names

Fix two staging drivers to use module_init()/module_exit()
instead of default init_module() and cleanup_module() function names
so that there are no name conflicts when both are built-in.

drivers/staging/dt3155/built-in.o: In function `cleanup_module':
(.text+0xc0): multiple definition of `cleanup_module'
drivers/staging/batman-adv/built-in.o:(.text+0x330): first defined here
drivers/staging/dt3155/built-in.o: In function `init_module':
(.text+0xe60): multiple definition of `init_module'
drivers/staging/batman-adv/built-in.o:(.text+0x400): first defined here

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
[sven.eckelmann@gmx.de: Mark module init and exit functions as static]
Signed-off-by: Sven Eckelmann <sven.eckelmann@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>