staging: brcm80211: use local variable for socitype during ai_scan

The SOC interface type is only needed to verify that we are accessing
a chip with AMBA AXI interconnect during ai_scan function. Therefor
this can be done with a local variable.

Cc: devel@linuxdriverproject.org
Cc: linux-wireless@vger.kernel.org
Cc: Brett Rudley <brudley@broadcom.com>
Cc: Henry Ptasinski <henryp@broadcom.com>
Cc: Roland Vossen <rvossen@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>