habanalabs: initialize variable to default value

Fix the following smatch error in unmap_device_va():
error: uninitialized symbol 'rc'.
Signed-off-by: Tomer Tayar <ttayar@habana.ai>
Reviewed-by: Oded Gabbay <oded.gabbay@gmail.com>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>
Link: https://lore.kernel.org/r/20200601065648.8775-1-oded.gabbay@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/habanalabs/memory.c

@@ -1023,7 +1023,7 @@ static int unmap_device_va(struct hl_ctx *ctx, u64 vaddr, bool ctx_free)
 	struct hl_va_range *va_range;
 	enum vm_type_t *vm_type;
 	bool is_userptr;
-	int rc;
+	int rc = 0;
 
 	/* protect from double entrance */
 	mutex_lock(&ctx->mem_hash_lock);