staging: r8188eu: remove unused enum _NIC_VERSION

None of these enumerated values were used anywhere in the driver, so
just remove them all.

Link: https://lore.kernel.org/r/20210730092417.1014392-9-gregkh@linuxfoundation.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/r8188eu/include/drv_types.h

@@ -40,13 +40,6 @@
 
 #define DRIVERVERSION	"v4.1.4_6773.20130222"
 
-enum _NIC_VERSION {
-	RTL8711_NIC,
-	RTL8712_NIC,
-	RTL8713_NIC,
-	RTL8716_NIC
-};
-
 #define SPEC_DEV_ID_NONE		BIT(0)
 #define SPEC_DEV_ID_DISABLE_HT		BIT(1)
 #define SPEC_DEV_ID_ENABLE_PS		BIT(2)