Staging: dgap: Remove unused variable

This patch removes variable that was used to store only the return value of a function call.

The issue was detected and resolved using the following coccinelle script:

@@
expression ret;
identifier f;
@@

-ret =
+return
	f(...);
-return ret;

Signed-off-by: Haneen Mohammed <hamohammed.sa@gmail.com>
Reviewed-by: Daniel Baluta <daniel.baluta@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>