Staging: rt2860: Fix remaining build warnings

Fixed remaining four build warnings in drivers/staging/rt2860/:

drivers/staging/rt2860/common/mlme.c:900: warning: format ‘%d’ expects type ‘int’, but argument 2 has type ‘ULONG’
drivers/staging/rt2860/common/rtmp_init.c:2049: warning: ‘Value’ may be used uninitialized in this function
drivers/staging/rt2860/sta_ioctl.c:361: warning: ‘return’ with a value, in function returning void
drivers/staging/rt2860/sta_ioctl.c:2468: warning: ‘return’ with a value, in function returning void

Signed-off-by: Mark Einon <mark.einon@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>