Staging: brcm80211: fix up compiler warnings I created

I messed up on some of the uintptr conversions, this fixes them up
properly.

Cc: Brett Rudley <brudley@broadcom.com>
Cc: Henry Ptasinski <henryp@broadcom.com>
Cc: Nohee Ko <noheek@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>