dell-wmi: Add support for eject key on Dell Studio 1555

Fixes pressing the eject key on Dell Studio 1555 does not work and produces
message :

dell-wmi: Unknown key 0 pressed

Signed-off-by: Islam Amer <pharon@gmail.com>
diff --git a/drivers/platform/x86/dell-wmi.c b/drivers/platform/x86/dell-wmi.c
index 66f53c3..12a8e6f 100644
--- a/drivers/platform/x86/dell-wmi.c
+++ b/drivers/platform/x86/dell-wmi.c
@@ -221,7 +221,7 @@
 			return;
 		}
 
-		if (dell_new_hk_type)
+		if (dell_new_hk_type || buffer_entry[1] == 0x0)
 			reported_key = (int)buffer_entry[2];
 		else
 			reported_key = (int)buffer_entry[1] & 0xffff;