ath11k: return -ENOMEM on allocation failure

Returning PTR_ERR(NULL) means success, but we should return -ENOMEM.

Fixes: 1399fb87 ("ath11k: register MHI controller device for QCA6390")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200826113417.GE393664@mwanda

drivers/net/wireless/ath/ath11k/mhi.c

@@ -220,7 +220,7 @@ int ath11k_mhi_register(struct ath11k_pci *ab_pci)
 
 	mhi_ctrl = kzalloc(sizeof(*mhi_ctrl), GFP_KERNEL);
 	if (!mhi_ctrl)
-		return PTR_ERR(mhi_ctrl);
+		return -ENOMEM;
 
 	ath11k_core_create_firmware_path(ab, ATH11K_AMSS_FILE,
 					 ab_pci->amss_path,