[PATCH] staging: wilc1000: restore wilc_spi_dev variable

[Arnd Bergmann]

A recent change to wilc1000 accidentally deleted an important
variable, so we now get a build error when the SPI mode is
selected:

ERROR: "wilc_spi_dev" [drivers/staging/wilc1000/wilc1000.ko] undefined!

This partially reverts the broken commit to put the variable back.

Signed-off-by: Arnd Bergmann <arnd at arndb.de>
Fixes: 56293ff232b9 ("staging: wilc1000: linux_wlan_spi: include header")
---
Found on ARM randconfig builds.

diff --git a/drivers/staging/wilc1000/linux_wlan_spi.c b/drivers/staging/wilc1000/linux_wlan_spi.c
index 760b72a9a6ff..039d06192d6b 100644
--- a/drivers/staging/wilc1000/linux_wlan_spi.c
+++ b/drivers/staging/wilc1000/linux_wlan_spi.c
@@ -41,6 +41,7 @@
 
 static u32 SPEED = MIN_SPEED;
 
+struct spi_device *wilc_spi_dev;
 void linux_spi_deinit(void *vp);
 
 static int __init wilc_bus_probe(struct spi_device *spi)