drivers/intel/wifi: Only compile if SMBIOS tables are generated

drivers/intel/wifi: Only compile if SMBIOS tables are generated

This driver adds an SMBIOS table for Intel WiFi, but if SMBIOS
table generation is disabled then it should not attempt to
compile or it will fail to find the "get_smbios_data" member
of the device_operations structure.

Tested by compiling and booting on purism/librem13 with
SMBIOS table generation disabled.

Change-Id: Iac6c265da7daae1be4d7585dab7b54561ff4e631
Signed-off-by: Duncan Laurie <dlaurie@google.com>
Reviewed-on: https://review.coreboot.org/13046
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>