staging: brcm80211: remove osl source files from driver

The whole need for the OSL concept has been removed from the driver. This
is the final commit removing the source file and include file from the
driver repository. All include statements of osl.h have been removed from
the other source files.

Reviewed-by: Brett Rudley <brudley@broadcom.com>
Reviewed-by: Henry Ptasinski <henryp@broadcom.com>
Reviewed-by: Roland Vossen <rvossen@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>